diff --git a/docs/sphinx_doc/source/tutorial/trinity_configs.md b/docs/sphinx_doc/source/tutorial/trinity_configs.md
index c2c4593d23..2a74f6f92a 100644
--- a/docs/sphinx_doc/source/tutorial/trinity_configs.md
+++ b/docs/sphinx_doc/source/tutorial/trinity_configs.md
@@ -174,7 +174,7 @@ model:
 - `max_response_tokens`: Maximum number of tokens allowed in generated responses. Only for `chat` and `generate` methods in `InferenceModel`.
 - `max_prompt_tokens`: Maximum number of tokens allowed in prompts. Only for `chat` and `generate` methods in `InferenceModel`.
 - `min_response_tokens`: Minimum number of tokens allowed in generated responses. Only for `chat` and `generate` methods in `InferenceModel`. Default is `1`. It must be less than `max_response_tokens`.
-- `enable_prompt_truncation`: Whether to truncate the prompt. Default is `true`. If set to `true`, the prompt will be truncated to `max_prompt_tokens` tokens; if set to `false`, the prompt will not be truncated and there is a risk that the prompt length plus response length exceeds `max_model_len`.
+- `enable_prompt_truncation`: Whether to truncate the prompt. Default is `true`. If set to `true`, the prompt will be truncated to `max_prompt_tokens` tokens; if set to `false`, the prompt will not be truncated and there is a risk that the prompt length plus response length exceeds `max_model_len`. This function does not work with openai api mode.
 
 ```{tip}
 If you are using the openai API provided by Explorer, only `max_model_len` will take effect, and the value of `max_response_tokens`, `max_prompt_tokens`, and `min_response_tokens` will be ignored. When `max_tokens` is not independently specified, each API call will generate up to `max_model_len - prompt_length` tokens. Therefore, please ensure that the prompt length is less than `max_model_len` when using the API.
diff --git a/docs/sphinx_doc/source_zh/tutorial/trinity_configs.md b/docs/sphinx_doc/source_zh/tutorial/trinity_configs.md
index 10f836fa62..804c2527a7 100644
--- a/docs/sphinx_doc/source_zh/tutorial/trinity_configs.md
+++ b/docs/sphinx_doc/source_zh/tutorial/trinity_configs.md
@@ -174,7 +174,7 @@ model:
 - `max_prompt_tokens`: 输入 prompt 中允许的最大 token 数。仅对 `InferenceModel` 中的 `chat` 和 `generate` 方法生效。
 - `max_response_tokens`: 模型生成的回复中允许的最大 token 数。仅对 `InferenceModel` 中的 `chat` 和 `generate` 方法生效。
 - `min_response_tokens`: 模型生成的回复中允许的最小 token 数。仅对 `InferenceModel` 中的 `chat` 和 `generate` 方法生效。
-- `enable_prompt_truncation`: 是否截断 prompt。默认为 `true`。若设置为 `true`，则 prompt 将被截断为 `max_prompt_tokens` 个 token；若设置为 `false`，则 prompt 不会被截断，存在 prompt 和 response 长度之和超过 `max_model_len` 的风险。
+- `enable_prompt_truncation`: 是否截断 prompt。默认为 `true`。若设置为 `true`，则 prompt 将被截断为 `max_prompt_tokens` 个 token；若设置为 `false`，则 prompt 不会被截断，存在 prompt 和 response 长度之和超过 `max_model_len` 的风险。在 OpenAI API 模式下不生效。
 
 ```{tip}
 如果使用的是 Explorer 提供的 openai API，则只有 `max_model_len` 会生效，而 `max_response_tokens`、`max_prompt_tokens` 和 `min_response_tokens` 的值将被忽略，在没有独立指定 `max_tokens` 时，每次 API 调用将生成最多 `max_model_len - prompt_length` 个 token，因此在使用时请确保 prompt 长度小于 `max_model_len`。
diff --git a/tests/common/experience_test.py b/tests/common/experience_test.py
index 826c29d546..195aaa61ae 100644
--- a/tests/common/experience_test.py
+++ b/tests/common/experience_test.py
@@ -175,7 +175,7 @@ def test_assertions(self):
         # prompt_length must be > 0
         with self.assertRaises(AssertionError):
             Experience(tokens=[1, 2, 3], prompt_length=0)
-        # tokens must be longer than prompt_length for single-turn
+        # tokens must be larger than prompt_length for single-turn
         with self.assertRaises(AssertionError):
             Experience(tokens=[1, 2], prompt_length=2)
         # DPO: tokens must match prompt_length
diff --git a/tests/common/vllm_test.py b/tests/common/vllm_test.py
index 2f281f4b32..ef3a5e7f7a 100644
--- a/tests/common/vllm_test.py
+++ b/tests/common/vllm_test.py
@@ -224,6 +224,7 @@ async def test_generate(
     [
         (20, 19, None),
         (20, None, 1),
+        (20, 5, 15),
     ],
 )
 class TestModelLen(RayUnittestBaseAysnc):
@@ -240,6 +241,7 @@ def setUp(self):
 
         self.engines, self.auxiliary_engines = create_inference_models(self.config)
         self.model_wrapper = ModelWrapper(self.engines[0], engine_type="vllm", enable_history=True)
+        self.tokenizer = AutoTokenizer.from_pretrained(self.config.model.model_path)
 
     async def test_model_len(self):
         await self.model_wrapper.prepare()
@@ -248,18 +250,30 @@ async def test_model_len(self):
             {"role": "user", "content": "What's the weather like today?"},
         ]
 
+        def _check_experience(exp):
+            # check prompt content and length
+            encoded_prompt = self.tokenizer.encode(exp.prompt_text, add_special_tokens=False)
+            self.assertEqual(len(encoded_prompt), exp.prompt_length)
+            self.assertLessEqual(exp.prompt_length, self.config.model.max_prompt_tokens)
+            # check response content and length
+            encoded_response = self.tokenizer.encode(exp.response_text, add_special_tokens=False)
+            self.assertEqual(len(encoded_response), len(exp.tokens) - exp.prompt_length)
+            self.assertLessEqual(
+                len(exp.tokens) - exp.prompt_length, self.config.model.max_response_tokens
+            )
+            # check full sequence
+            self.assertLessEqual(len(exp.tokens), self.config.model.max_model_len)
+
         # For vllm engine, max_prompt_tokens and max_response_tokens work
         response = self.model_wrapper.chat(messages)
         self.assertEqual(len(response), 1)
-        self.assertEqual(len(response[0].tokens), self.config.model.max_model_len)
+        if self.max_prompt_tokens == 5:
+            self.assertEqual(response[0].truncate_status, "prompt_truncated")
+        _check_experience(response[0])
+
         exps = self.model_wrapper.extract_experience_from_history()
         self.assertEqual(len(exps), 1)
-        # check prompt length, response length, max_model_len
-        self.assertEqual(exps[0].prompt_length, self.config.model.max_prompt_tokens)
-        self.assertEqual(
-            len(exps[0].tokens) - exps[0].prompt_length, self.config.model.max_response_tokens
-        )
-        self.assertLessEqual(len(response[0].tokens), self.config.model.max_model_len)
+        _check_experience(exps[0])
 
         # For openai api, max_prompt_tokens and max_response_tokens do not work
         openai_client = self.model_wrapper.get_openai_client()
diff --git a/tests/trainer/trainer_test.py b/tests/trainer/trainer_test.py
index a873401599..8a87efe759 100644
--- a/tests/trainer/trainer_test.py
+++ b/tests/trainer/trainer_test.py
@@ -1043,3 +1043,44 @@ def test_trainer(self):
     def tearDown(self):
         # remove dir only when the test passed
         shutil.rmtree(self.config.checkpoint_job_dir)
+
+
+class TestTrainerPromptTruncation(BaseTrainerCase):
+    def test_trainer(self):
+        self.config.model.max_model_len = 20
+        self.config.model.max_prompt_tokens = 5
+        self.config.model.max_response_tokens = 15
+        self.config.model.enable_prompt_truncation = True
+        self.config.algorithm.algorithm_type = "grpo"
+        self.config.algorithm.advantage_fn = "grpo"
+        self.config.algorithm.kl_loss_fn = "none"
+        self.config.algorithm.repeat_times = 2
+        self.config.buffer.batch_size = 4
+        self.config.buffer.total_steps = 2
+        self.config.buffer.explorer_input.taskset = get_unittest_dataset_config("gsm8k")
+        self.config.check_and_update()
+        both(self.config)
+
+        parser = TensorBoardParser(os.path.join(self.config.monitor.cache_dir, "tensorboard"))
+        rollout_metrics = parser.metric_list("rollout")
+        self.assertTrue(len(rollout_metrics) > 0)
+        self.assertEqual(parser.metric_max_step(rollout_metrics[0]), 2)
+        actor_metrics = parser.metric_list("actor")
+        self.assertTrue(len(actor_metrics) > 0)
+        self.assertEqual(parser.metric_max_step(actor_metrics[0]), 2)
+        max_prompt_length = parser.metric_values("prompt_length/max")
+        self.assertEqual(max(max_prompt_length), 5)
+        min_prompt_length = parser.metric_values("prompt_length/min")
+        self.assertEqual(min(min_prompt_length), 5)
+        max_response_length = parser.metric_values("response_length/max")
+        self.assertEqual(max(max_response_length), 1)
+        min_response_length = parser.metric_values("response_length/min")
+        self.assertEqual(min(min_response_length), 1)
+        final_loss = parser.metric_values("actor/final_loss")
+        self.assertEqual(final_loss[0], 0.0)
+        grad_norm = parser.metric_values("actor/grad_norm")
+        self.assertEqual(grad_norm[0], 0.0)
+
+    def tearDown(self):
+        # remove dir only when the test passed
+        shutil.rmtree(self.config.checkpoint_job_dir)
diff --git a/trinity/common/config.py b/trinity/common/config.py
index 8ea02095f7..f63f57c2f4 100644
--- a/trinity/common/config.py
+++ b/trinity/common/config.py
@@ -457,7 +457,8 @@ class ModelConfig:
     max_response_tokens: Optional[int] = None
     # the minimum number of tokens for the response
     min_response_tokens: int = 1
-    # whether to truncate the prompt; if set to True, the prompt will be truncated to `max_prompt_tokens` tokens.
+    # whether to truncate the prompt; if set to True, the prompt will be truncated to `max_prompt_tokens` tokens;
+    # not applicable for OpenAI API
     enable_prompt_truncation: bool = True
 
     # lora config
@@ -1192,7 +1193,7 @@ def _check_model(self) -> None:
         if model.enable_prompt_truncation is True:
             if model.max_prompt_tokens is None:
                 raise ValueError(
-                    "When `model.enable_prompt_truncation` is True, `model.max_prompt_tokens` must be set properly."
+                    "When `model.enable_prompt_truncation` is True, `model.max_prompt_tokens` must be set properly. This function does not work with OpenAI API mode."
                 )
             logger.warning(
                 f"`enable_prompt_truncation` is set to True; the prompt will be truncated to `max_prompt_tokens`={model.max_prompt_tokens} tokens if it is too long."
diff --git a/trinity/common/experience.py b/trinity/common/experience.py
index 4e3aa936be..2a734144d2 100644
--- a/trinity/common/experience.py
+++ b/trinity/common/experience.py
@@ -104,6 +104,9 @@ class Experience:
     token_level_reward: Optional[Tensor] = None  # [resp_length]
     advantages: Optional[Tensor] = None  # [resp_length]
     returns: Optional[Tensor] = None  # [resp_length]
+    truncate_status: Optional[
+        str
+    ] = None  # The status of truncation, e.g., "prompt_truncated", "response_truncated"; Not working for openai api
     info: dict = field(
         default_factory=dict
     )  # Additional information about the experience, can also be used to store custom fields
@@ -140,6 +143,7 @@ def __init__(  # noqa: C901
         token_level_reward=None,
         advantages=None,
         returns=None,
+        truncate_status=None,
         info=None,
         metrics=None,
         prompt_length=1,
@@ -165,10 +169,13 @@ def __init__(  # noqa: C901
             assert (
                 prompt_length > 0
             ), "Prompt length must be greater than 0 for single-turn experiences."
-            assert (
-                len(tokens) > prompt_length
-            ), f"Token ids must be longer than the prompt length. Got len(tokens)={len(tokens)}, prompt_length={prompt_length}."
-            action_mask = torch.ones(len(tokens) - prompt_length, dtype=torch.bool)
+            if truncate_status != "prompt_truncated":
+                assert (
+                    len(tokens) > prompt_length
+                ), f"Token ids must be larger than the prompt length. Got len(tokens)={len(tokens)}, prompt_length={prompt_length}."
+                action_mask = torch.ones(len(tokens) - prompt_length, dtype=torch.bool)
+            else:
+                action_mask = torch.zeros(len(logprobs), dtype=torch.bool)
         elif experience_type == "dpo":
             prompt_length = len(tokens)
         if eid is None:
@@ -196,6 +203,7 @@ def __init__(  # noqa: C901
         self.experience_type = experience_type
         self.info = info or {}
         self.metrics = metrics or {}
+        self.truncate_status = truncate_status
         self.prompt_length = prompt_length
         self.response_text = response_text
         self.prompt_text = prompt_text
@@ -264,6 +272,8 @@ def to_dict(self) -> dict:
             res["rejected_messages"] = self.rejected_messages
         if self.reward is not None:
             res["reward"] = float(self.reward)
+        if self.truncate_status is not None:
+            res["truncate_status"] = self.truncate_status
         return res
 
     @classmethod
diff --git a/trinity/common/models/vllm_model.py b/trinity/common/models/vllm_model.py
index aefafb315b..ba6ccf0f5f 100644
--- a/trinity/common/models/vllm_model.py
+++ b/trinity/common/models/vllm_model.py
@@ -191,12 +191,36 @@ async def generate(
         """
         if self.tokenizer is None:
             await self._initialize_tokenizer()
+
+        # Tokenize once without truncation to check if truncation is needed
         token_ids = self.tokenizer(  # type: ignore
             prompt,
-            truncation=self.config.enable_prompt_truncation,
-            max_length=self.config.max_prompt_tokens,
+            truncation=False,
             return_tensors="pt",
-        )["input_ids"][0].tolist()
+        )[
+            "input_ids"
+        ][0].tolist()
+
+        # Check if truncation is needed and apply it
+        if self.config.enable_prompt_truncation and self.config.max_prompt_tokens is not None:
+            if len(token_ids) > self.config.max_prompt_tokens:
+                self.logger.warning(
+                    f"Prompt was truncated to {self.config.max_prompt_tokens} tokens"
+                )
+                token_ids = token_ids[: self.config.max_prompt_tokens + 1]  # leave one for response
+                return [
+                    Experience(
+                        tokens=token_ids,
+                        logprobs=torch.zeros(1, dtype=torch.float32),
+                        prompt_length=len(token_ids) - 1,
+                        prompt_text=self.tokenizer.decode(token_ids[:-1]),
+                        response_text=self.tokenizer.decode(token_ids[-1]),
+                        truncate_status="prompt_truncated",
+                        reward=0.0,
+                    )
+                    for i in range(kwargs.get("n", 1))
+                ]
+
         output = await self._generate_internal(
             prompt={"prompt_token_ids": token_ids}, lora_request=lora_request, **kwargs
         )
@@ -397,10 +421,10 @@ async def convert_messages_to_experience(
 
         # Truncate tokens if they exceed the length limit
         assert token_ids is not None
-        is_truncated = False  # TODO: add to experience itself
+        truncate_status = None
         if self.config.max_model_len is not None and self.config.max_model_len > 0:
             if len(token_ids) > self.config.max_model_len - 1:
-                is_truncated = True
+                truncate_status = "response_truncated"
                 self.logger.warning(
                     f"Warning: {len(token_ids) = } exceeds the length limit {self.config.max_model_len-1 = }"
                 )
@@ -417,7 +441,7 @@ async def convert_messages_to_experience(
             prompt_length=prompt_length,
             action_mask=action_mask[prompt_length:],  # Exclude the prompt tokens
             messages=messages,
-            info={"is_truncated": is_truncated},
+            truncate_status=truncate_status,
         )
 
     async def shutdown(self):
diff --git a/trinity/common/workflows/envs/frozen_lake/workflow.py b/trinity/common/workflows/envs/frozen_lake/workflow.py
index 35fc8bce98..c7a13c17fd 100644
--- a/trinity/common/workflows/envs/frozen_lake/workflow.py
+++ b/trinity/common/workflows/envs/frozen_lake/workflow.py
@@ -280,6 +280,7 @@ async def run_async(self) -> List[Experience]:
         self.step_count = 0
         self.action = None
         terminate_reason = None
+        truncate_status = None
 
         # Initialize messages
         messages = []
@@ -318,6 +319,7 @@ async def run_async(self) -> List[Experience]:
                 self.done = False
                 self.step_rewards.append(0)
                 terminate_reason = "max_tokens_reached"
+                truncate_status = "response_truncated"
                 break
 
             # Get action from the model
@@ -360,6 +362,7 @@ async def run_async(self) -> List[Experience]:
                 "env_done": 1 if self.done else 0,
                 "test_score": final_reward,
             },
+            truncate_status=truncate_status,
         )
         return [experience]
 
diff --git a/trinity/common/workflows/workflow.py b/trinity/common/workflows/workflow.py
index 0798c3e65a..90f52a2505 100644
--- a/trinity/common/workflows/workflow.py
+++ b/trinity/common/workflows/workflow.py
@@ -165,10 +165,12 @@ def set_repeat_times(self, repeat_times, run_id_base):
         self.repeat_times = repeat_times
         self.run_id_base = run_id_base
 
-    def process_messages_to_experience(self, messages, reward, info={}) -> Experience:
+    def process_messages_to_experience(
+        self, messages, reward, info={}, truncate_status=None
+    ) -> Experience:
         converted_experience = self.model.convert_messages_to_experience(messages)
 
-        if converted_experience.info.get("is_truncated", False):
+        if converted_experience.truncate_status == "response_truncated":
             reward = 0.0
 
         tokens = converted_experience.tokens
@@ -188,6 +190,7 @@ def process_messages_to_experience(self, messages, reward, info={}) -> Experienc
             prompt_length=converted_experience.prompt_length,
             prompt_text=converted_experience.prompt_text,
             response_text=converted_experience.response_text,
+            truncate_status=converted_experience.truncate_status or truncate_status,
             reward=reward,
             logprobs=log_probs,
             info=info,
diff --git a/trinity/trainer/verl/utils.py b/trinity/trainer/verl/utils.py
index 9a35eb8a29..ab50b7c877 100644
--- a/trinity/trainer/verl/utils.py
+++ b/trinity/trainer/verl/utils.py
@@ -154,7 +154,10 @@ def compute_data_metrics(batch: DataProto, use_critic: bool = False) -> dict:
     if "advantages" in batch.batch:
         # adv
         advantages = batch.batch["advantages"]
-        valid_adv = torch.masked_select(advantages, response_mask)
+        if response_mask.numel() > 0:
+            valid_adv = torch.masked_select(advantages, response_mask)
+        else:
+            valid_adv = torch.zeros(1)
         metrics.update(
             {
                 # adv
@@ -166,7 +169,10 @@ def compute_data_metrics(batch: DataProto, use_critic: bool = False) -> dict:
     if "returns" in batch.batch:
         # returns
         returns = batch.batch["returns"]
-        valid_returns = torch.masked_select(returns, response_mask)
+        if response_mask.numel() > 0:
+            valid_returns = torch.masked_select(returns, response_mask)
+        else:
+            valid_returns = torch.zeros(1)
         metrics.update(
             {
                 "critic/returns/mean": torch.mean(valid_returns).detach().item(),