diff --git a/dargs/dargs.py b/dargs/dargs.py
index 20930eb..caf8dc6 100644
--- a/dargs/dargs.py
+++ b/dargs/dargs.py
@@ -952,12 +952,15 @@ def gen_doc_flag(self, path: list[str] | None = None, **kwargs) -> str:
         choicedoc = indent("| possible choices: " + ", ".join(l_choice), INDENT)
         realdoc = indent(self.doc + "\n", INDENT) if self.doc else None
         anchor = make_rst_refid(arg_path) if kwargs.get("make_anchor") else None
-        abstractdoc = "\n".join(
-            [
-                f"* {ll}: {cc.doc}"
-                for ll, cc in zip(l_choice, self.choice_dict.values())
-                if cc.doc
-            ]
+        abstractdoc = indent(
+            "\n".join(
+                [
+                    f"* {ll}: {cc.doc}"
+                    for ll, cc in zip(l_choice, self.choice_dict.values())
+                    if cc.doc
+                ]
+            ),
+            INDENT,
         )
         allparts = [
             anchor,