diff --git a/backend/community/models.py b/backend/community/models.py
index e8a1800..6c00bfa 100644
--- a/backend/community/models.py
+++ b/backend/community/models.py
@@ -50,10 +50,11 @@ class Activity(models.Model):
     @property
     def display_banner_url(self):
         """
-        获取Banner显示的URL，优先使用上传的图片
+        获取Banner显示的URL，优先使用上传的图片，返回相对路径避免容器内部地址
         """
-        if self.banner:
-            return self.banner.url
+        if self.banner and self.banner.name:
+            from django.conf import settings
+            return settings.MEDIA_URL + self.banner.name
         return self.banner_url
 
     @property
diff --git a/backend/competition/admin.py b/backend/competition/admin.py
index 31373f0..55dfdb6 100644
--- a/backend/competition/admin.py
+++ b/backend/competition/admin.py
@@ -7,12 +7,13 @@ from .models import Competition, CompetitionEnrollment, ScoreDimension, Project,
 
 @admin.register(HomePageConfig)
 class HomePageConfigAdmin(ModelAdmin):
-    list_display = ['id', 'main_title', 'organizer', 'undertaker', 'is_active']
+    list_display = ['id', 'main_title', 'organizer', 'undertaker', 'is_active', 'banner_preview']
     list_editable = ['main_title', 'organizer', 'undertaker', 'is_active']
+    readonly_fields = ['banner_preview']
     fieldsets = (
         ('封面图', {
-            'fields': ('banner_image', 'banner_image_url'),
-            'description': '首页标题下方的封面图，可上传本地图片或填写URL'
+            'fields': ('banner_image', 'banner_image_url', 'banner_preview'),
+            'description': '首页标题下方的封面图，可上传本地图片或填写URL，优先使用上传的图片'
         }),
         ('标题设置', {
             'fields': ('main_title',)
@@ -25,6 +26,18 @@ class HomePageConfigAdmin(ModelAdmin):
         }),
     )
 
+    @display(description="封面图预览")
+    def banner_preview(self, obj):
+        url = None
+        if obj.banner_image and obj.banner_image.name:
+            from django.conf import settings
+            url = settings.MEDIA_URL + obj.banner_image.name
+        elif obj.banner_image_url:
+            url = obj.banner_image_url
+        if url:
+            return format_html('<img src="{}" style="max-height:120px;max-width:300px;border-radius:6px;object-fit:cover;" />', url)
+        return "暂无图片"
+
 
 class ScoreDimensionInline(admin.TabularInline):
     model = ScoreDimension
diff --git a/backend/competition/serializers.py b/backend/competition/serializers.py
index bf2391e..c3c3937 100644
--- a/backend/competition/serializers.py
+++ b/backend/competition/serializers.py
@@ -17,7 +17,8 @@ class HomePageConfigSerializer(serializers.ModelSerializer):
     class Meta:
         model = HomePageConfig
         fields = ['id', 'banner_image', 'banner_image_url', 'display_banner',
-                  'main_title', 'organizer', 'undertaker']
+                  'main_title', 'organizer', 'undertaker', 'is_active']
+
     def get_display_banner(self, obj):
         return _media_url(obj.banner_image) or obj.banner_image_url
 
diff --git a/backend/competition/views.py b/backend/competition/views.py
index 8abf7da..4ac2fe7 100644
--- a/backend/competition/views.py
+++ b/backend/competition/views.py
@@ -14,14 +14,24 @@ from .serializers import (
 from rest_framework.pagination import PageNumberPagination
 
 
-@api_view(['GET'])
+@api_view(['GET', 'PATCH'])
 @permission_classes([permissions.AllowAny])
 def get_homepage_config(request):
-    """获取首页配置"""
+    """获取或更新首页配置（PATCH 支持 multipart/form-data 上传图片）"""
     try:
         config = HomePageConfig.objects.filter(is_active=True).first()
         if not config:
             config = HomePageConfig.objects.create()
+
+        if request.method == 'PATCH':
+            serializer = HomePageConfigSerializer(
+                config, data=request.data, partial=True, context={'request': request}
+            )
+            if serializer.is_valid():
+                serializer.save()
+                return Response(serializer.data)
+            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
+
         serializer = HomePageConfigSerializer(config, context={'request': request})
         return Response(serializer.data)
     except Exception as e:
diff --git a/frontend/src/components/activity/ActivityCard.jsx b/frontend/src/components/activity/ActivityCard.jsx
index 0b04e00..c090dc5 100644
--- a/frontend/src/components/activity/ActivityCard.jsx
+++ b/frontend/src/components/activity/ActivityCard.jsx
@@ -7,9 +7,8 @@ const { Title } = Typography;
 
 const getImageUrl = (url) => {
   if (!url) return '';
-  if (url.startsWith('http') || url.startsWith('//')) {
-    try { return new URL(url).pathname; } catch { return url; }
-  }
+  // 外部 URL 直接返回，不提取 pathname
+  if (url.startsWith('http') || url.startsWith('//')) return url;
   return url;
 };
 
diff --git a/frontend/src/pages/activity/Detail.jsx b/frontend/src/pages/activity/Detail.jsx
index 8817d02..188396c 100644
--- a/frontend/src/pages/activity/Detail.jsx
+++ b/frontend/src/pages/activity/Detail.jsx
@@ -396,8 +396,7 @@ const ActivityDetail = () => {
 
       {/* Hero Image with LayoutId for shared transition */}
       <div className={styles.detailHeader}>
-        <motion.img
-          layoutId={`activity-card-${id}`}
+        <img
           src={activity.display_banner_url || cleanUrl(activity.banner_url) || activity.cover_image || 'https://images.unsplash.com/photo-1540575467063-178a50c2df87?w=800&h=600&fit=crop'}
           alt={activity.title}
           className={styles.detailImage}