diff --git a/src/llm_models/model_client/openai_client.py b/src/llm_models/model_client/openai_client.py
index 33b2505e..664380b8 100644
--- a/src/llm_models/model_client/openai_client.py
+++ b/src/llm_models/model_client/openai_client.py
@@ -565,7 +565,7 @@ class OpenaiClient(BaseClient):
         self,
         model_info: ModelInfo,
         audio_base64: str,
-        max_tokens: int = 2048,  # OpenAI 实际不用
+        max_tokens: Optional[int] = None,
         extra_params: dict[str, Any] | None = None,
     ) -> APIResponse:
         """