diff --git a/apps/application/chat_pipeline/step/chat_step/i_chat_step.py b/apps/application/chat_pipeline/step/chat_step/i_chat_step.py
index 18b08ea7a..55ba166cf 100644
--- a/apps/application/chat_pipeline/step/chat_step/i_chat_step.py
+++ b/apps/application/chat_pipeline/step/chat_step/i_chat_step.py
@@ -53,7 +53,7 @@ class IChatStep(IBaseChatPipelineStep):
         # 对话列表
         message_list = serializers.ListField(required=True, child=MessageField(required=True),
                                              error_messages=ErrMessage.list("对话列表"))
-        model_id = serializers.UUIDField(required=True, error_messages=ErrMessage.uuid("模型id"))
+        model_id = serializers.UUIDField(required=False, allow_null=True, error_messages=ErrMessage.uuid("模型id"))
         # 段落列表
         paragraph_list = serializers.ListField(error_messages=ErrMessage.list("段落列表"))
         # 对话id
diff --git a/apps/application/chat_pipeline/step/chat_step/impl/base_chat_step.py b/apps/application/chat_pipeline/step/chat_step/impl/base_chat_step.py
index 750335e2d..2667d34a2 100644
--- a/apps/application/chat_pipeline/step/chat_step/impl/base_chat_step.py
+++ b/apps/application/chat_pipeline/step/chat_step/impl/base_chat_step.py
@@ -111,7 +111,7 @@ class BaseChatStep(IChatStep):
                 client_id=None, client_type=None,
                 no_references_setting=None,
                 **kwargs):
-        chat_model = get_model_instance_by_model_user_id(model_id, user_id)
+        chat_model = get_model_instance_by_model_user_id(model_id, user_id) if model_id is not None else None
         if stream:
             return self.execute_stream(message_list, chat_id, problem_text, post_response_handler, chat_model,
                                        paragraph_list,