diff --git a/src/Oms.Application/Shared/WeChatRegistrationFieldNormalizer.cs b/src/Oms.Application/Shared/WeChatRegistrationFieldNormalizer.cs
index 1d7d9ff..789884e 100644
--- a/src/Oms.Application/Shared/WeChatRegistrationFieldNormalizer.cs
+++ b/src/Oms.Application/Shared/WeChatRegistrationFieldNormalizer.cs
@@ -8,10 +8,15 @@ public static class WeChatRegistrationFieldNormalizer
     public const int CustomerNameMaxLength = 128;
     public const int PhoneMaxLength = 16;
     public const int EmailMaxLength = 64;
-    public const int AvatarMaxLength = 255;
+    /// <summary>客户表 WechatAvatar 列长度。</summary>
+    public const int CustomerWechatAvatarMaxLength = 255;
     public const int NicknameMaxLength = 64;
     public const int OpenidMaxLength = 64;
 
+    /// <summary>微信头像仅写入 t_customer；RBAC user.Avatar 列更短，注册时不写入。</summary>
+    public static string? NormalizeCustomerWechatAvatar(string? avatar) =>
+        TruncateOptional(avatar, CustomerWechatAvatarMaxLength);
+
     public static string TruncateRequired(string value, int maxLength)
     {
         var normalized = value.Trim();
diff --git a/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs b/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
index 91c2494..2decf16 100644
--- a/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
+++ b/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
@@ -98,9 +98,7 @@ public class WeChatCustomerService(
         var wechatNickname = WeChatRegistrationFieldNormalizer.TruncateOptional(
             input.Wechat.Nickname,
             WeChatRegistrationFieldNormalizer.NicknameMaxLength);
-        var wechatAvatar = WeChatRegistrationFieldNormalizer.TruncateOptional(
-            input.Wechat.Avatar,
-            WeChatRegistrationFieldNormalizer.AvatarMaxLength);
+        var wechatAvatar = WeChatRegistrationFieldNormalizer.NormalizeCustomerWechatAvatar(input.Wechat.Avatar);
 
         if (password.Length < 6)
         {
@@ -126,7 +124,6 @@ public class WeChatCustomerService(
                 Account = phone,
                 Password = password,
                 Email = email,
-                Avatar = wechatAvatar,
                 RoleIds = [customerRoleId]
             });
 
@@ -170,8 +167,15 @@ public class WeChatCustomerService(
 
         var account = NormalizeRequired(input.Account, "账号");
         var password = NormalizeRequired(input.Password, "密码");
+        var wechatOpenid = WeChatRegistrationFieldNormalizer.TruncateRequired(
+            input.Wechat.Openid.Trim(),
+            WeChatRegistrationFieldNormalizer.OpenidMaxLength);
+        var wechatNickname = WeChatRegistrationFieldNormalizer.TruncateOptional(
+            input.Wechat.Nickname,
+            WeChatRegistrationFieldNormalizer.NicknameMaxLength);
+        var wechatAvatar = WeChatRegistrationFieldNormalizer.NormalizeCustomerWechatAvatar(input.Wechat.Avatar);
 
-        if (await customerRepository.GetByWechatOpenidAsync(input.Wechat.Openid, cancellationToken) != null)
+        if (await customerRepository.ExistsWechatOpenidAnyAsync(wechatOpenid, cancellationToken))
         {
             throw new BusinessException("当前微信已绑定账号");
         }
@@ -199,9 +203,9 @@ public class WeChatCustomerService(
             throw new BusinessException("账号或密码错误");
         }
 
-        customer.WechatOpenid = input.Wechat.Openid;
-        customer.WechatNickname = NormalizeOptional(input.Wechat.Nickname) ?? customer.WechatNickname;
-        customer.WechatAvatar = NormalizeOptional(input.Wechat.Avatar) ?? customer.WechatAvatar;
+        customer.WechatOpenid = wechatOpenid;
+        customer.WechatNickname = wechatNickname ?? customer.WechatNickname;
+        customer.WechatAvatar = wechatAvatar ?? customer.WechatAvatar;
         await customerRepository.UpdateAsync(customer, cancellationToken);
     }