diff --git a/app/Console/Commands/ResetPassword.php b/app/Console/Commands/ResetPassword.php
index 86e14a5..3e131f2 100644
--- a/app/Console/Commands/ResetPassword.php
+++ b/app/Console/Commands/ResetPassword.php
@@ -43,7 +43,7 @@ class ResetPassword extends Command
     public function handle()
     {
         $password = $this->argument('password') ;
-        $user = User::where('email', $this->argument('email'))->first();
+        $user = User::byEmail($this->argument('email'))->first();
         if (!$user) abort(500, '邮箱不存在');
         $password = $password ?? Helper::guid(false);
         $user->password = password_hash($password, PASSWORD_DEFAULT);
diff --git a/app/Http/Controllers/V1/Passport/CommController.php b/app/Http/Controllers/V1/Passport/CommController.php
index 65365d8..663badf 100644
--- a/app/Http/Controllers/V1/Passport/CommController.php
+++ b/app/Http/Controllers/V1/Passport/CommController.php
@@ -29,7 +29,7 @@ class CommController extends Controller
 
         // 检查白名单后缀限制
         if ((int) admin_setting('email_whitelist_enable', 0)) {
-            $isRegisteredEmail = User::where('email', $email)->exists();
+            $isRegisteredEmail = User::byEmail($email)->exists();
             if (!$isRegisteredEmail) {
                 $allowedSuffixes = Helper::getEmailSuffix();
                 $emailSuffix = substr(strrchr($email, '@'), 1);
diff --git a/app/Http/Controllers/V2/Admin/OrderController.php b/app/Http/Controllers/V2/Admin/OrderController.php
index 1d3ad3d..c06c7c8 100644
--- a/app/Http/Controllers/V2/Admin/OrderController.php
+++ b/app/Http/Controllers/V2/Admin/OrderController.php
@@ -199,7 +199,7 @@ class OrderController extends Controller
     public function assign(OrderAssign $request)
     {
         $plan = Plan::find($request->input('plan_id'));
-        $user = User::where('email', $request->input('email'))->first();
+        $user = User::byEmail($request->input('email'))->first();
 
         if (!$user) {
             return $this->fail([400202, '该用户不存在']);
diff --git a/app/Http/Controllers/V2/Admin/UserController.php b/app/Http/Controllers/V2/Admin/UserController.php
index 68cc05b..45bd9b7 100644
--- a/app/Http/Controllers/V2/Admin/UserController.php
+++ b/app/Http/Controllers/V2/Admin/UserController.php
@@ -220,7 +220,7 @@ class UserController extends Controller
             return $this->fail([400202, '用户不存在']);
         }
         if (isset($params['email'])) {
-            if (User::where('email', $params['email'])->first() && $user->email !== $params['email']) {
+            if (User::byEmail($params['email'])->first() && $user->email !== $params['email']) {
                 return $this->fail([400201, '邮箱已被使用']);
             }
         }
@@ -240,7 +240,7 @@ class UserController extends Controller
             $params['group_id'] = $plan->group_id;
         }
         // 处理邀请用户
-        if ($request->input('invite_user_email') && $inviteUser = User::where('email', $request->input('invite_user_email'))->first()) {
+        if ($request->input('invite_user_email') && $inviteUser = User::byEmail($request->input('invite_user_email'))->first()) {
             $params['invite_user_id'] = $inviteUser->id;
         } else {
             $params['invite_user_id'] = null;
@@ -365,7 +365,7 @@ class UserController extends Controller
         if ($request->input('email_prefix')) {
             $email = $request->input('email_prefix') . '@' . $request->input('email_suffix');
 
-            if (User::where('email', $email)->exists()) {
+            if (User::byEmail($email)->exists()) {
                 return $this->fail([400201, '邮箱已存在于系统中']);
             }
 
diff --git a/app/Models/User.php b/app/Models/User.php
index 4d6aad2..a826e4a 100755
--- a/app/Models/User.php
+++ b/app/Models/User.php
@@ -3,6 +3,8 @@
 namespace App\Models;
 
 use App\Utils\Helper;
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Casts\Attribute;
 use Illuminate\Foundation\Auth\User as Authenticatable;
 use Laravel\Sanctum\HasApiTokens;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
@@ -81,6 +83,20 @@ class User extends Authenticatable
     public const COMMISSION_TYPE_SYSTEM = 0;
     public const COMMISSION_TYPE_PERIOD = 1;
     public const COMMISSION_TYPE_ONETIME = 2;
+    protected function email(): Attribute
+    {
+        return Attribute::make(
+            set: fn (string $value) => strtolower(trim($value)),
+        );
+    }
+
+    /**
+     * 按邮箱查询（大小写不敏感，兼容所有数据库）
+     */
+    public function scopeByEmail(Builder $query, string $email): Builder
+    {
+        return $query->where('email', strtolower(trim($email)));
+    }
 
     // 获取邀请人信息
     public function invite_user(): BelongsTo
diff --git a/app/Services/Auth/LoginService.php b/app/Services/Auth/LoginService.php
index bd8a6cd..363e82b 100644
--- a/app/Services/Auth/LoginService.php
+++ b/app/Services/Auth/LoginService.php
@@ -36,7 +36,7 @@ class LoginService
         }
 
         // 查找用户
-        $user = User::where('email', $email)->first();
+        $user = User::byEmail($email)->first();
         if (!$user) {
             return [false, [400, __('Incorrect email or password')]];
         }
@@ -99,7 +99,7 @@ class LoginService
         }
 
         // 查找用户
-        $user = User::where('email', $email)->first();
+        $user = User::byEmail($email)->first();
         if (!$user) {
             return [false, [400, __('This email is not registered in the system')]];
         }
diff --git a/app/Services/Auth/MailLinkService.php b/app/Services/Auth/MailLinkService.php
index e2351e0..259ced7 100644
--- a/app/Services/Auth/MailLinkService.php
+++ b/app/Services/Auth/MailLinkService.php
@@ -27,7 +27,7 @@ class MailLinkService
             return [false, [429, __('Sending frequently, please try again later')]];
         }
 
-        $user = User::where('email', $email)->first();
+        $user = User::byEmail($email)->first();
         if (!$user) {
             return [true, true]; // 成功但用户不存在，保护用户隐私
         }
diff --git a/app/Services/Auth/RegisterService.php b/app/Services/Auth/RegisterService.php
index a87b56a..78d207e 100644
--- a/app/Services/Auth/RegisterService.php
+++ b/app/Services/Auth/RegisterService.php
@@ -91,8 +91,7 @@ class RegisterService
         }
 
         // 检查邮箱是否存在
-        $email = $request->input('email');
-        $exist = User::where('email', $email)->first();
+        $exist = User::byEmail($request->input('email'))->first();
         if ($exist) {
             return [false, [400201, __('Email already exists')]];
         }
diff --git a/database/migrations/2026_03_28_050000_lowercase_existing_emails.php b/database/migrations/2026_03_28_050000_lowercase_existing_emails.php
new file mode 100644
index 0000000..07eee3d
--- /dev/null
+++ b/database/migrations/2026_03_28_050000_lowercase_existing_emails.php
@@ -0,0 +1,38 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Log;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        // 统计需要转换的记录数
+        $count = DB::table('v2_user')
+            ->whereNotNull('email')
+            ->whereRaw('email != LOWER(email)')
+            ->count();
+
+        if ($count > 0) {
+            Log::info("Converting {$count} email(s) to lowercase");
+            DB::table('v2_user')
+                ->whereNotNull('email')
+                ->whereRaw('email != LOWER(email)')
+                ->update(['email' => DB::raw('LOWER(email)')]);
+                
+            Log::info("Email lowercase conversion completed");
+        }
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        // 无法恢复原始大小写
+    }
+};