diff --git a/app/db/paper_trading.py b/app/db/paper_trading.py
index 1630974..1463bc0 100644
--- a/app/db/paper_trading.py
+++ b/app/db/paper_trading.py
@@ -1171,6 +1171,12 @@ def _periodized_return_pct(total_return_pct: float, running_days: float, period_
     return round((growth ** (period_days / running_days) - 1) * 100, 4)
 
 
+def _periodized_return_label(total_return_pct: float, running_days: float, period_days: float) -> str:
+    if running_days < 30:
+        return "样本不足"
+    return _fmt_pct(_periodized_return_pct(total_return_pct, running_days, period_days))
+
+
 def send_paper_trading_report(days: int = 30) -> dict:
     days = max(1, min(_safe_int(days, 30), 365))
     summary = get_paper_trading_summary(days=days)
@@ -1186,8 +1192,10 @@ def send_paper_trading_report(days: int = 30) -> dict:
     return_pct = _safe_float(summary.get("account_total_return_pct"))
     win_rate = _safe_float(summary.get("win_rate"))
     running_days = _paper_running_days()
-    monthly_return_pct = _periodized_return_pct(return_pct, running_days, 30)
-    annualized_return_pct = _periodized_return_pct(return_pct, running_days, 365)
+    monthly_return_pct = _periodized_return_pct(return_pct, running_days, 30) if running_days >= 30 else None
+    annualized_return_pct = _periodized_return_pct(return_pct, running_days, 365) if running_days >= 30 else None
+    monthly_return_label = _periodized_return_label(return_pct, running_days, 30)
+    annualized_return_label = _periodized_return_label(return_pct, running_days, 365)
     template = "green" if total_pnl >= 0 else "red"
     elements = [
         {
@@ -1206,8 +1214,8 @@ def send_paper_trading_report(days: int = 30) -> dict:
             "background_style": "default",
             "columns": [
                 {"tag": "column", "width": "weighted", "weight": 1, "elements": [_card_field("账户收益率", _fmt_pct(return_pct))]},
-                {"tag": "column", "width": "weighted", "weight": 1, "elements": [_card_field("月化收益率", _fmt_pct(monthly_return_pct))]},
-                {"tag": "column", "width": "weighted", "weight": 1, "elements": [_card_field("年化收益率", _fmt_pct(annualized_return_pct))]},
+                {"tag": "column", "width": "weighted", "weight": 1, "elements": [_card_field("月化收益率", monthly_return_label)]},
+                {"tag": "column", "width": "weighted", "weight": 1, "elements": [_card_field("年化收益率", annualized_return_label)]},
             ],
         },
         {
@@ -1250,6 +1258,8 @@ def send_paper_trading_report(days: int = 30) -> dict:
         "running_days": running_days,
         "monthly_return_pct": monthly_return_pct,
         "annualized_return_pct": annualized_return_pct,
+        "monthly_return_label": monthly_return_label,
+        "annualized_return_label": annualized_return_label,
         "summary": summary,
         "sent_at": _now(),
         "push_result": push_result,
diff --git a/tests/test_paper_trading.py b/tests/test_paper_trading.py
index e14f257..67374c9 100644
--- a/tests/test_paper_trading.py
+++ b/tests/test_paper_trading.py
@@ -428,8 +428,10 @@ def test_send_paper_trading_report_pushes_performance_summary(monkeypatch, buy_n
 
     assert result["ok"] is True
     assert result["running_days"] >= 1
-    assert "monthly_return_pct" in result
-    assert "annualized_return_pct" in result
+    assert result["monthly_return_pct"] is None
+    assert result["annualized_return_pct"] is None
+    assert result["monthly_return_label"] == "样本不足"
+    assert result["annualized_return_label"] == "样本不足"
     assert pushed[-1]["metadata"]["event_type"] == "trade_report"
     text = _visible_card_text(pushed[-1])
     assert "交易报告" in text