diff --git a/src/Oms.Application/Shared/OmsRbacRegistrationGuard.cs b/src/Oms.Application/Shared/OmsRbacRegistrationGuard.cs
new file mode 100644
index 0000000..f47ce1d
--- /dev/null
+++ b/src/Oms.Application/Shared/OmsRbacRegistrationGuard.cs
@@ -0,0 +1,118 @@
+using Fake.Application;
+using Fake.Rbac.Infrastructure;
+using Microsoft.EntityFrameworkCore;
+
+namespace Oms.Application.Shared;
+
+/// <summary>
+/// 微信/客户注册前校验 RBAC 登录账号，避免 user 表已存在但 t_customer 未创建时 EF 抛出英文 DbUpdateException。
+/// </summary>
+public static class OmsRbacRegistrationGuard
+{
+    public static async Task EnsureLoginIdentityAvailableAsync(
+        FakeRbacDbContext rbacDbContext,
+        string account,
+        string? email,
+        CancellationToken cancellationToken = default)
+    {
+        var normalizedAccount = account.Trim();
+        var normalizedEmail = string.IsNullOrWhiteSpace(email) ? null : email.Trim();
+
+        if (await ExistsActiveUserByAccountAsync(rbacDbContext, normalizedAccount, cancellationToken))
+        {
+            throw new BusinessException("登录账号已存在，请直接绑定或使用其他手机号");
+        }
+
+        if (normalizedEmail != null
+            && await ExistsActiveUserByEmailAsync(rbacDbContext, normalizedEmail, cancellationToken))
+        {
+            throw new BusinessException("邮箱已被占用，请更换邮箱或直接绑定已有账号");
+        }
+    }
+
+    public static BusinessException ToSaveBusinessException(Exception ex)
+    {
+        var message = ExtractDeepMessage(ex);
+        if (ContainsDuplicateKey(message))
+        {
+            if (message.Contains("Account", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("uk_user_account", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("IX_user_Account", StringComparison.OrdinalIgnoreCase))
+            {
+                return new BusinessException("登录账号已存在，请直接绑定或使用其他手机号");
+            }
+
+            if (message.Contains("Email", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("uk_user_email", StringComparison.OrdinalIgnoreCase))
+            {
+                return new BusinessException("邮箱已被占用，请更换邮箱或直接绑定已有账号");
+            }
+
+            if (message.Contains("Phone", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("uk_cus_phone", StringComparison.OrdinalIgnoreCase))
+            {
+                return new BusinessException("手机号已存在");
+            }
+
+            if (message.Contains("uk_cus_email", StringComparison.OrdinalIgnoreCase))
+            {
+                return new BusinessException("邮箱已存在");
+            }
+
+            if (message.Contains("WechatOpenid", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("uk_cus_openid", StringComparison.OrdinalIgnoreCase)
+                || message.Contains("uk_customer_wechat_openid", StringComparison.OrdinalIgnoreCase))
+            {
+                return new BusinessException("当前微信已绑定账号");
+            }
+
+            return new BusinessException("账号信息已存在，请直接绑定或更换手机号/邮箱");
+        }
+
+        return new BusinessException("注册失败，请稍后重试或联系客服");
+    }
+
+    private static async Task<bool> ExistsActiveUserByAccountAsync(
+        FakeRbacDbContext rbacDbContext,
+        string account,
+        CancellationToken cancellationToken)
+    {
+        var hit = await rbacDbContext.Database
+            .SqlQuery<int?>(
+                $"SELECT 1 AS Value FROM `user` WHERE `IsDeleted` = 0 AND `Account` = {account} LIMIT 1")
+            .FirstOrDefaultAsync(cancellationToken);
+        return hit.HasValue;
+    }
+
+    private static async Task<bool> ExistsActiveUserByEmailAsync(
+        FakeRbacDbContext rbacDbContext,
+        string email,
+        CancellationToken cancellationToken)
+    {
+        var hit = await rbacDbContext.Database
+            .SqlQuery<int?>(
+                $"SELECT 1 AS Value FROM `user` WHERE `IsDeleted` = 0 AND `Email` = {email} LIMIT 1")
+            .FirstOrDefaultAsync(cancellationToken);
+        return hit.HasValue;
+    }
+
+    private static string ExtractDeepMessage(Exception ex)
+    {
+        var parts = new List<string>();
+        for (var current = ex; current != null; current = current.InnerException)
+        {
+            if (!string.IsNullOrWhiteSpace(current.Message))
+            {
+                parts.Add(current.Message);
+            }
+        }
+
+        return string.Join(" | ", parts);
+    }
+
+    private static bool ContainsDuplicateKey(string message) =>
+        message.Contains("Duplicate entry", StringComparison.OrdinalIgnoreCase)
+        || message.Contains("1062", StringComparison.OrdinalIgnoreCase)
+        || message.Contains("unique constraint", StringComparison.OrdinalIgnoreCase)
+        || message.Contains("UNIQUE constraint failed", StringComparison.OrdinalIgnoreCase);
+}
diff --git a/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs b/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
index 7eaf2b7..ce02226 100644
--- a/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
+++ b/src/SimpleAdmin.Api/WeChat/WeChatCustomerService.cs
@@ -97,6 +97,7 @@ public class WeChatCustomerService(
 
         var customerCode = await CustomerCodeGenerator.GenerateNextAsync(customerRepository, cancellationToken);
         await EnsureCustomerIdentityUniqueAsync(customerCode, phone, email, cancellationToken);
+        await OmsRbacRegistrationGuard.EnsureLoginIdentityAvailableAsync(rbacDbContext, phone, email, cancellationToken);
 
         var customerRoleId = await GetCustomerRoleIdOrThrowAsync(cancellationToken);
         var user = await userService.CreateAsync(new UserCreateDto
@@ -128,10 +129,10 @@ public class WeChatCustomerService(
             };
             await customerRepository.InsertAsync(entity);
         }
-        catch
+        catch (Exception ex)
         {
             await TryRollbackRbacUserAsync(user.Id);
-            throw;
+            throw ex is BusinessException ? ex : OmsRbacRegistrationGuard.ToSaveBusinessException(ex);
         }
     }