diff --git a/doc/changes/repo-tree-default-branch.md b/doc/changes/repo-tree-default-branch.md
new file mode 100644
index 0000000..0bd9e05
--- /dev/null
+++ b/doc/changes/repo-tree-default-branch.md
@@ -0,0 +1,18 @@
+# repo +tree 遵循仓库默认分支
+
+## 背景
+
+`repo +tree` 未指定 `--ref` 时把 ref 硬编码为 `master`，对默认分支是
+`main`（或其他名称）的仓库直接返回 `[-2] 你访问的文件不存在`
+（生产实测 `datawhalechina/paper-chart-tutorial`，默认分支 `main`）。
+平台 `sub_entries` API 在不带 `ref` 参数时会自动使用仓库默认分支。
+
+## 变更
+
+- `--ref` 未指定时不再发送 `ref` 参数（交由平台落到默认分支），flag 也不再
+  声明 `master` 默认值。
+
+## 验证
+
+- `go test ./shortcuts/repo/`（默认 ref 断言改为「不携带 ref 参数」）
+- 生产 gitlink.org.cn 实测：默认分支为 `main` 与 `master` 的仓库均正常列出根目录。
diff --git a/shortcuts/repo/repo.go b/shortcuts/repo/repo.go
index 06774a6..ebf6ced 100644
--- a/shortcuts/repo/repo.go
+++ b/shortcuts/repo/repo.go
@@ -86,21 +86,19 @@ func Shortcuts(translators ...*i18n.Translator) []*common.Shortcut {
 			Description: tr.T("cmd.repo.tree.short"),
 			Flags: []common.Flag{
 				{Name: "path", Short: "p", Usage: tr.T("flag.repo.tree.path")},
-				{Name: "ref", Short: "r", Usage: tr.T("flag.repo.tree.ref"), Default: "master"},
+				{Name: "ref", Short: "r", Usage: tr.T("flag.repo.tree.ref")},
 			},
 			Run: func(ctx *common.RuntimeContext) error {
 				if err := ctx.ResolveOwnerRepo(); err != nil {
 					return err
 				}
 				q := url.Values{}
-				ref := ctx.Arg("ref")
-				if ref == "" {
-					ref = "master"
-				}
 				if path := ctx.Arg("path"); path != "" {
 					q.Set("filepath", path)
 				}
-				q.Set("ref", ref)
+				if ref := ctx.Arg("ref"); ref != "" {
+					q.Set("ref", ref)
+				}
 				env, err := ctx.CallAPIWithQuery("GET", ctx.RepoPath()+"/sub_entries", q)
 				if err != nil {
 					return err
diff --git a/shortcuts/repo/repo_test.go b/shortcuts/repo/repo_test.go
index 5c5f34b..27312fe 100644
--- a/shortcuts/repo/repo_test.go
+++ b/shortcuts/repo/repo_test.go
@@ -158,7 +158,9 @@ func TestRepoTreeListsRootOnDefaultRef(t *testing.T) {
 		if _, ok := r.URL.Query()["filepath"]; ok {
 			t.Fatalf("did not expect filepath query for repository root, got %q", r.URL.Query().Get("filepath"))
 		}
-		assertEqual(t, r.URL.Query().Get("ref"), "master")
+		if _, ok := r.URL.Query()["ref"]; ok {
+			t.Fatalf("did not expect ref query for default ref, got %q", r.URL.Query().Get("ref"))
+		}
 		writeJSON(t, w, map[string]interface{}{
 			"entries": []map[string]interface{}{
 				{"name": "README.md", "type": "file"},
@@ -213,7 +215,7 @@ func TestRepoTreeShortcutRegistersHelpFlags(t *testing.T) {
 	if !ok {
 		t.Fatal("tree shortcut missing ref flag")
 	}
-	if refFlag.Short != "r" || refFlag.Default != "master" || refFlag.Usage == "" {
+	if refFlag.Short != "r" || refFlag.Default != "" || refFlag.Usage == "" {
 		t.Fatalf("unexpected ref flag: %+v", refFlag)
 	}
 }