diff --git a/models/repo.go b/models/repo.go
index 8ba48f7a3..f32b42ef7 100755
--- a/models/repo.go
+++ b/models/repo.go
@@ -956,6 +956,33 @@ func IsRepositoryExist(u *User, repoName string, alias string) (bool, error) {
 	return isRepositoryExist(x, u, repoName, alias)
 }
 
+// IsRepositoryAliasExist returns true if the repository with given alias under user has already existed.
+func IsRepositoryAliasExist(u *User, alias string) (bool, error) {
+	return isRepositoryAliasExist(x, u, alias)
+}
+
+func isRepositoryAliasExist(e Engine, u *User, alias string) (bool, error) {
+	var cond = builder.NewCond()
+	cond = cond.And(builder.Eq{"owner_id": u.ID})
+	cond = cond.And(builder.Eq{"alias": alias})
+	count, err := e.Where(cond).Count(&Repository{})
+	return count > 0, err
+}
+
+func IsRepositoryAliasAvailable(doer *User, alias string) error {
+	if err := IsUsableRepoAlias(alias); err != nil {
+		return err
+	}
+
+	has, err := IsRepositoryAliasExist(doer, alias)
+	if err != nil {
+		return fmt.Errorf("IsRepositoryExist: %v", err)
+	} else if has {
+		return ErrRepoAlreadyExist{doer.Name, alias}
+	}
+	return nil
+}
+
 // CloneLink represents different types of clone URLs of repository.
 type CloneLink struct {
 	SSH   string
diff --git a/routers/repo/setting.go b/routers/repo/setting.go
index 055627fc1..f9461be0d 100644
--- a/routers/repo/setting.go
+++ b/routers/repo/setting.go
@@ -67,6 +67,28 @@ func SettingsPost(ctx *context.Context, form auth.RepoSettingForm) {
 			return
 		}
 
+		newAlias := form.Alias
+		// Check if repository alias has been changed.
+		if repo.Alias != newAlias {
+			//check new alias is available or not
+			if err := models.IsRepositoryAliasAvailable(ctx.Repo.Owner, newAlias); err != nil {
+				ctx.Data["Err_Alias"] = true
+				switch {
+				case models.IsErrRepoAlreadyExist(err):
+					ctx.RenderWithErr(ctx.Tr("form.repo_name_been_taken"), tplSettingsOptions, &form)
+				case models.IsErrNameReserved(err):
+					ctx.RenderWithErr(ctx.Tr("repo.form.name_reserved", err.(models.ErrNameReserved).Name), tplSettingsOptions, &form)
+				case models.IsErrNamePatternNotAllowed(err):
+					ctx.RenderWithErr(ctx.Tr("repo.form.name_pattern_not_allowed", err.(models.ErrNamePatternNotAllowed).Pattern), tplSettingsOptions, &form)
+				default:
+					ctx.ServerError("ChangeRepositoryName", err)
+				}
+				return
+			}
+
+			log.Trace("Repository alias changed: %s/%s -> %s", ctx.Repo.Owner.Name, repo.Alias, newAlias)
+		}
+
 		newRepoName := form.RepoName
 		// Check if repository name has been changed.
 		if repo.LowerName != strings.ToLower(newRepoName) {
@@ -92,13 +114,14 @@ func SettingsPost(ctx *context.Context, form auth.RepoSettingForm) {
 
 			log.Trace("Repository name changed: %s/%s -> %s", ctx.Repo.Owner.Name, repo.Name, newRepoName)
 		}
+
 		// In case it's just a case change.
 		repo.Name = newRepoName
 		repo.LowerName = strings.ToLower(newRepoName)
 		repo.Description = form.Description
 		repo.Website = form.Website
 		repo.IsTemplate = form.Template
-		repo.Alias = form.Alias
+		repo.Alias = newAlias
 
 		// Visibility of forked repository is forced sync with base repository.
 		if repo.IsFork {