diff --git a/model/task_cas_test.go b/model/task_cas_test.go
index 052bf638..54ec7bda 100644
--- a/model/task_cas_test.go
+++ b/model/task_cas_test.go
@@ -45,6 +45,7 @@ func TestMain(m *testing.M) {
 		&SubscriptionPlan{},
 		&SubscriptionOrder{},
 		&UserSubscription{},
+		&UserOAuthBinding{},
 		&PerfMetric{},
 	); err != nil {
 		panic("failed to migrate: " + err.Error())
@@ -66,6 +67,7 @@ func truncateTables(t *testing.T) {
 		DB.Exec("DELETE FROM subscription_orders")
 		DB.Exec("DELETE FROM subscription_plans")
 		DB.Exec("DELETE FROM user_subscriptions")
+		DB.Exec("DELETE FROM user_oauth_bindings")
 		DB.Exec("DELETE FROM perf_metrics")
 	})
 }
diff --git a/model/user.go b/model/user.go
index a50fab0d..53f93b02 100644
--- a/model/user.go
+++ b/model/user.go
@@ -328,8 +328,12 @@ func HardDeleteUserById(id int) error {
 	if id == 0 {
 		return errors.New("id 为空！")
 	}
-	err := DB.Unscoped().Delete(&User{}, "id = ?", id).Error
-	return err
+	return DB.Transaction(func(tx *gorm.DB) error {
+		if err := deleteUserOAuthBindingsByUserId(tx, id); err != nil {
+			return err
+		}
+		return tx.Unscoped().Delete(&User{}, "id = ?", id).Error
+	})
 }
 
 func inviteUser(inviterId int) (err error) {
@@ -589,8 +593,12 @@ func (user *User) HardDelete() error {
 	if user.Id == 0 {
 		return errors.New("id 为空！")
 	}
-	err := DB.Unscoped().Delete(user).Error
-	return err
+	return DB.Transaction(func(tx *gorm.DB) error {
+		if err := deleteUserOAuthBindingsByUserId(tx, user.Id); err != nil {
+			return err
+		}
+		return tx.Unscoped().Delete(user).Error
+	})
 }
 
 // ValidateAndFill check password & user status
diff --git a/model/user_oauth_binding.go b/model/user_oauth_binding.go
index 49216625..cc337995 100644
--- a/model/user_oauth_binding.go
+++ b/model/user_oauth_binding.go
@@ -10,9 +10,9 @@ import (
 // UserOAuthBinding stores the binding relationship between users and custom OAuth providers
 type UserOAuthBinding struct {
 	Id             int       `json:"id" gorm:"primaryKey"`
-	UserId         int       `json:"user_id" gorm:"not null;uniqueIndex:ux_user_provider"`                                        // User ID - one binding per user per provider
-	ProviderId     int       `json:"provider_id" gorm:"not null;uniqueIndex:ux_user_provider;uniqueIndex:ux_provider_userid"`     // Custom OAuth provider ID
-	ProviderUserId string    `json:"provider_user_id" gorm:"type:varchar(256);not null;uniqueIndex:ux_provider_userid"`           // User ID from OAuth provider - one OAuth account per provider
+	UserId         int       `json:"user_id" gorm:"not null;uniqueIndex:ux_user_provider"`                                    // User ID - one binding per user per provider
+	ProviderId     int       `json:"provider_id" gorm:"not null;uniqueIndex:ux_user_provider;uniqueIndex:ux_provider_userid"` // Custom OAuth provider ID
+	ProviderUserId string    `json:"provider_user_id" gorm:"type:varchar(256);not null;uniqueIndex:ux_provider_userid"`       // User ID from OAuth provider - one OAuth account per provider
 	CreatedAt      time.Time `json:"created_at"`
 }
 
@@ -134,9 +134,8 @@ func DeleteUserOAuthBinding(userId, providerId int) error {
 	return DB.Where("user_id = ? AND provider_id = ?", userId, providerId).Delete(&UserOAuthBinding{}).Error
 }
 
-// DeleteUserOAuthBindingsByUserId deletes all OAuth bindings for a user
-func DeleteUserOAuthBindingsByUserId(userId int) error {
-	return DB.Where("user_id = ?", userId).Delete(&UserOAuthBinding{}).Error
+func deleteUserOAuthBindingsByUserId(tx *gorm.DB, userId int) error {
+	return tx.Where("user_id = ?", userId).Delete(&UserOAuthBinding{}).Error
 }
 
 // GetBindingCountByProviderId returns the number of bindings for a provider