diff --git a/backend/meetings/views.py b/backend/meetings/views.py
index 8bd7eecf..58688b93 100644
--- a/backend/meetings/views.py
+++ b/backend/meetings/views.py
@@ -165,7 +165,7 @@ class MeetingViewSet(viewsets.ModelViewSet):
         # 检查是否已加入
         existing = Participant.objects.filter(
             meeting=meeting,
-            user=request.user,
+            user_id=None,
             left_at__isnull=True
         ).first()
         
@@ -175,7 +175,7 @@ class MeetingViewSet(viewsets.ModelViewSet):
         # 创建参会记录
         participant = Participant.objects.create(
             meeting=meeting,
-            user=request.user,
+            user_id=None,
             agent_type='human',
             nickname=request.user.username
         )