diff --git a/backend/apps/exports/utils.py b/backend/apps/exports/utils.py
index cba0f5a..25722b6 100644
--- a/backend/apps/exports/utils.py
+++ b/backend/apps/exports/utils.py
@@ -296,8 +296,14 @@ def draw_joker(canvas, design, which, project, card_key, asset):
     """绘制大小王：独立背景 + 主体图 + 文字"""
     w, h = canvas.size
 
-    # 优先用单牌覆盖的背景色
-    bg_color = design.get('background_color', '#1B5E20' if which == 'big' else '#B71C1C')
+    # 大小王默认有自己的背景色（绿/红），不被整副牌的 background_color 覆盖
+    # 除非用户显式在 card_overrides 里设了 background_color
+    default_bg = '#1B5E20' if which == 'big' else '#B71C1C'
+    card_overrides = (project.card_overrides or {}).get(card_key, {})
+    if 'background_color' in card_overrides:
+        bg_color = card_overrides['background_color']
+    else:
+        bg_color = default_bg
     canvas.paste(hex_to_rgba(bg_color, 255), (0, 0, w, h))
 
     # 主体图