diff --git a/controller/oauth.go b/controller/oauth.go
index faa22dd4f..0bb33d2cd 100644
--- a/controller/oauth.go
+++ b/controller/oauth.go
@@ -240,7 +240,10 @@ func findOrCreateOAuthUser(c *gin.Context, provider oauth.Provider, oauthUser *o
 
 	if oauthUser.Username != "" {
 		if exists, err := model.CheckUserExistOrDeleted(oauthUser.Username, ""); err == nil && !exists {
-			user.Username = oauthUser.Username
+			// 防止索引退化
+			if len(oauthUser.Username) <= model.UserNameMaxLength {
+				user.Username = oauthUser.Username
+			}
 		}
 	}
 
@@ -302,12 +305,12 @@ func findOrCreateOAuthUser(c *gin.Context, provider oauth.Provider, oauthUser *o
 			// Set the provider user ID on the user model and update
 			provider.SetProviderUserID(user, oauthUser.ProviderUserID)
 			if err := tx.Model(user).Updates(map[string]interface{}{
-				"github_id":    user.GitHubId,
-				"discord_id":   user.DiscordId,
-				"oidc_id":      user.OidcId,
-				"linux_do_id":  user.LinuxDOId,
-				"wechat_id":    user.WeChatId,
-				"telegram_id":  user.TelegramId,
+				"github_id":   user.GitHubId,
+				"discord_id":  user.DiscordId,
+				"oidc_id":     user.OidcId,
+				"linux_do_id": user.LinuxDOId,
+				"wechat_id":   user.WeChatId,
+				"telegram_id": user.TelegramId,
 			}).Error; err != nil {
 				return err
 			}
diff --git a/model/user.go b/model/user.go
index e0c9c686f..f5ba5cebe 100644
--- a/model/user.go
+++ b/model/user.go
@@ -15,6 +15,8 @@ import (
 	"gorm.io/gorm"
 )
 
+const UserNameMaxLength = 20
+
 // User if you add sensitive fields, don't forget to clean them in setupLogin function.
 // Otherwise, the sensitive information will be saved on local storage in plain text!
 type User struct {