diff --git a/src/admin/pages/UserDetailPage.tsx b/src/admin/pages/UserDetailPage.tsx
index 2802852..073b6a5 100644
--- a/src/admin/pages/UserDetailPage.tsx
+++ b/src/admin/pages/UserDetailPage.tsx
@@ -25,7 +25,8 @@ export function UserDetailPage() {
   const [spaceQuotaMb, setSpaceQuotaMb] = useState('5');
   const [imageQuota, setImageQuota] = useState<ImageQuotaView | null>(null);
   const [imageQuotaLoading, setImageQuotaLoading] = useState(false);
-  const [imageGrant, setImageGrant] = useState({ delta: '', note: '' });
+  const [imageTotal, setImageTotal] = useState('');
+  const [imageGrantNote, setImageGrantNote] = useState('');
 
   useEffect(() => {
     if (!user?.spaceQuotaBytes) return;
@@ -82,6 +83,14 @@ export function UserDetailPage() {
     };
   }, [user?.id, user?.role]);
 
+  useEffect(() => {
+    if (!imageQuota || imageQuota.unlimited || imageQuota.total == null) {
+      setImageTotal('');
+      return;
+    }
+    setImageTotal(String(imageQuota.total));
+  }, [imageQuota?.total, imageQuota?.unlimited]);
+
   const handleRecharge = async (e: React.FormEvent) => {
     e.preventDefault();
     if (!user) return;
@@ -100,24 +109,42 @@ export function UserDetailPage() {
     }
   };
 
-  const handleImageGrant = async (e: React.FormEvent) => {
+  const handleImageQuotaSave = async (e: React.FormEvent) => {
     e.preventDefault();
     if (!user) return;
     setMessage(null);
     setLocalError(null);
     setError(null);
-    const delta = Math.floor(Number(imageGrant.delta));
-    if (!Number.isFinite(delta) || delta === 0) {
-      setLocalError('请输入非零整数额度');
+    if (!imageQuota) {
+      setLocalError('暂无额度信息，用户可能尚无有效订阅');
+      return;
+    }
+    if (imageQuota.unlimited) {
+      setLocalError('当前为无限额度套餐，无法在此调整');
+      return;
+    }
+    const targetTotal = Math.floor(Number(imageTotal));
+    if (!Number.isFinite(targetTotal) || targetTotal < 0) {
+      setLocalError('请输入非负整数总额度');
+      return;
+    }
+    if (targetTotal < imageQuota.used) {
+      setLocalError(`总额度不能低于已用量（${imageQuota.used} 张）`);
+      return;
+    }
+    const targetBonus = targetTotal - imageQuota.limit;
+    const delta = targetBonus - imageQuota.bonus;
+    if (delta === 0) {
+      setMessage('额度未变化');
       return;
     }
     try {
-      const result = await grantUserImageQuota(user.id, delta, imageGrant.note.trim());
+      const result = await grantUserImageQuota(user.id, delta, imageGrantNote.trim());
       setImageQuota(result.quota);
       setMessage('图片额度已更新');
-      setImageGrant({ delta: '', note: '' });
+      setImageGrantNote('');
     } catch (err) {
-      setLocalError(err instanceof Error ? err.message : '图片额度调整失败');
+      setLocalError(err instanceof Error ? err.message : '图片额度设置失败');
     }
   };
 
@@ -245,21 +272,31 @@ export function UserDetailPage() {
                 ) : (
                   <p className="muted">{imageQuotaSummary || '暂无额度信息（用户可能尚无订阅）'}</p>
                 )}
-                <form className="admin-form" onSubmit={handleImageGrant}>
+                <p className="muted">
+                  直接设置本周期图片总额度（套餐额度 + 额外充值）。已用量不变，修改后会反映在「充值」部分。
+                </p>
+                <form className="admin-form" onSubmit={handleImageQuotaSave}>
                   <input
-                    placeholder="调整额度（张，正数充值、负数扣减）"
+                    placeholder="图片总额度（张）"
                     type="number"
+                    min="0"
                     step="1"
-                    value={imageGrant.delta}
-                    onChange={(e) => setImageGrant((s) => ({ ...s, delta: e.target.value }))}
+                    value={imageTotal}
+                    onChange={(e) => setImageTotal(e.target.value)}
+                    disabled={!imageQuota || imageQuota.unlimited}
                   />
                   <input
                     placeholder="备注"
-                    value={imageGrant.note}
-                    onChange={(e) => setImageGrant((s) => ({ ...s, note: e.target.value }))}
+                    value={imageGrantNote}
+                    onChange={(e) => setImageGrantNote(e.target.value)}
+                    disabled={!imageQuota || imageQuota.unlimited}
                   />
-                  <button type="submit" className="send-btn">
-                    调整额度
+                  <button
+                    type="submit"
+                    className="send-btn"
+                    disabled={!imageQuota || imageQuota.unlimited}
+                  >
+                    保存额度
                   </button>
                 </form>
               </section>