diff --git a/apps/application/serializers/common.py b/apps/application/serializers/common.py
index 840a09b9e..7842c6b8d 100644
--- a/apps/application/serializers/common.py
+++ b/apps/application/serializers/common.py
@@ -127,8 +127,8 @@ class ChatInfo:
             'knowledge_id_list': self.knowledge_id_list,
             'exclude_document_id_list': self.exclude_document_id_list,
             'exclude_paragraph_id_list': [],
-            'top_n': knowledge_setting.get('top_n') or 3,
-            'similarity': knowledge_setting.get('similarity') or 0.6,
+            'top_n': 3 if knowledge_setting.get('top_n') is None else knowledge_setting.get('top_n'),
+            'similarity': 0.6 if knowledge_setting.get('similarity') is None else knowledge_setting.get('similarity'),
             'max_paragraph_char_number': knowledge_setting.get('max_paragraph_char_number') or 5000,
             'history_chat_record': self.chat_record_list,
             'chat_id': self.chat_id,