diff --git a/web/App_Code/api/adminUserController.cs b/web/App_Code/api/adminUserController.cs
index 1a56b61..013f6e4 100644
--- a/web/App_Code/api/adminUserController.cs
+++ b/web/App_Code/api/adminUserController.cs
@@ -90,14 +90,15 @@ public class adminUserController : ApiController
 
         if(q.removeExist.HasValue && q.removeExist.Value)
         {
-            var existingAdminNums = _db.members.Select(b => b.admin_num).ToList();
+            // 優化：使用子查詢在數據庫層面執行，避免載入所有會員的 admin_num
+            var usedAdminNums = _db.members.Select(b => b.admin_num);
             if (q.num.HasValue && q.num.Value > 0)
             {
-                qry = qry.Where(o => !existingAdminNums.Contains(o.num) || o.num == q.num.Value);
+                qry = qry.Where(o => !usedAdminNums.Contains(o.num) || o.num == q.num.Value);
             }
             else
             {
-                qry = qry.Where(o => !existingAdminNums.Contains(o.num));
+                qry = qry.Where(o => !usedAdminNums.Contains(o.num));
             }
         }