diff --git a/controller/user.go b/controller/user.go
index bf8a2a2..2810aaf 100644
--- a/controller/user.go
+++ b/controller/user.go
@@ -311,7 +311,7 @@ func GenerateAccessToken(c *gin.Context) {
 		})
 		return
 	}
-	user.AccessToken = common.GetUUID()
+	user.SetAccessToken(common.GetUUID())
 
 	if model.DB.Where("access_token = ?", user.AccessToken).First(user).RowsAffected != 0 {
 		c.JSON(http.StatusOK, gin.H{
diff --git a/model/main.go b/model/main.go
index 01eb6c9..6fe4e81 100644
--- a/model/main.go
+++ b/model/main.go
@@ -32,7 +32,7 @@ func createRootAccountIfNeed() error {
 			Role:        common.RoleRootUser,
 			Status:      common.UserStatusEnabled,
 			DisplayName: "Root User",
-			AccessToken: common.GetUUID(),
+			AccessToken: nil,
 			Quota:       100000000,
 		}
 		DB.Create(&rootUser)
diff --git a/model/user.go b/model/user.go
index 6d3b2b2..1905d89 100644
--- a/model/user.go
+++ b/model/user.go
@@ -25,7 +25,7 @@ type User struct {
 	WeChatId         string         `json:"wechat_id" gorm:"column:wechat_id;index"`
 	TelegramId       string         `json:"telegram_id" gorm:"column:telegram_id;index"`
 	VerificationCode string         `json:"verification_code" gorm:"-:all"`                                    // this field is only for Email verification, don't save it to database!
-	AccessToken      string         `json:"access_token" gorm:"type:char(32);column:access_token;uniqueIndex"` // this token is for system management
+	AccessToken      *string        `json:"access_token" gorm:"type:char(32);column:access_token;uniqueIndex"` // this token is for system management
 	Quota            int            `json:"quota" gorm:"type:int;default:0"`
 	UsedQuota        int            `json:"used_quota" gorm:"type:int;default:0;column:used_quota"` // used quota
 	RequestCount     int            `json:"request_count" gorm:"type:int;default:0;"`               // request number
@@ -38,6 +38,17 @@ type User struct {
 	DeletedAt        gorm.DeletedAt `gorm:"index"`
 }
 
+func (user *User) GetAccessToken() string {
+	if user.AccessToken == nil {
+		return ""
+	}
+	return *user.AccessToken
+}
+
+func (user *User) SetAccessToken(token string) {
+	user.AccessToken = &token
+}
+
 // CheckUserExistOrDeleted check if user exist or deleted, if not exist, return false, nil, if deleted or exist, return true, nil
 func CheckUserExistOrDeleted(username string, email string) (bool, error) {
 	var user User
@@ -201,7 +212,7 @@ func (user *User) Insert(inviterId int) error {
 		}
 	}
 	user.Quota = common.QuotaForNewUser
-	user.AccessToken = common.GetUUID()
+	//user.SetAccessToken(common.GetUUID())
 	user.AffCode = common.GetRandomString(4)
 	result := DB.Create(user)
 	if result.Error != nil {