diff --git a/sanguo_data/datawriter.py b/sanguo_data/datawriter.py
new file mode 100644
index 0000000..237abb0
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+++ b/sanguo_data/datawriter.py
@@ -0,0 +1,34 @@
+# sanguo_data/datawriter.py
+import os
+import pandas as pd
+from pathlib import Path
+from vnpy.trader.object import BarData
+from vnpy.trader.constant import Interval
+from sanguo_data.datareader import _row_to_bar
+from sanguo_data.config import DataConfig
+
+def atomic_write_parquet(path: str, df: pd.DataFrame) -> None:
+    p = Path(path)
+    p.parent.mkdir(parents=True, exist_ok=True)
+    tmp = str(p) + ".tmp"
+    df.to_parquet(tmp)
+    os.replace(tmp, str(p))  # 原子替换
+
+def write_daily(symbol: str, df: pd.DataFrame, cfg: DataConfig) -> None:
+    # 1) parquet 增量合并（按年分区，去重保留最新）
+    for year, group in df.groupby(df["date"].str[:4]):
+        f = Path(cfg.data_paths["daily_dir"]) / year / f"{symbol}.parquet"
+        if f.exists():
+            old = pd.read_parquet(f)
+            combined = pd.concat([old, group]).drop_duplicates("date", keep="last")
+        else:
+            combined = group
+        atomic_write_parquet(str(f), combined)
+    # 2) vnpy SQLite
+    bars = [_row_to_bar(symbol, row, Interval.DAILY) for _, row in df.iterrows()]
+    _save_to_vnpy_db(bars, cfg)
+
+def _save_to_vnpy_db(bars: list[BarData], cfg: DataConfig) -> None:
+    from vnpy.trader.database import get_database
+    db = get_database()
+    db.save_bar_data(bars)  # spike 验证签名
diff --git a/tests/data/test_datawriter.py b/tests/data/test_datawriter.py
new file mode 100644
index 0000000..58399e2
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+++ b/tests/data/test_datawriter.py
@@ -0,0 +1,24 @@
+# tests/data/test_datawriter.py
+import pandas as pd
+from sanguo_data.config import DataConfig
+from sanguo_data.datawriter import write_daily, atomic_write_parquet
+
+def test_atomic_write_parquet(tmp_path):
+    f = tmp_path / "2026" / "600000.parquet"
+    df = pd.DataFrame({"date": ["2026-01-01"], "open": [10.0]})
+    atomic_write_parquet(str(f), df)
+    assert f.exists()
+    assert not list(tmp_path.glob("*.tmp"))
+
+def test_write_daily_writes_parquet_and_db(tmp_path, monkeypatch):
+    cfg = DataConfig(
+        data_paths={"daily_dir": str(tmp_path / "daily"), "vnpy_db": str(tmp_path / "q.db")},
+        data_sources={}, validation={}, performance={},
+    )
+    df = pd.DataFrame({"date": ["2026-01-01"], "open": [10.0], "high": [10.0],
+                       "low": [10.0], "close": [10.0], "volume": [100]})
+    called = {}
+    monkeypatch.setattr("sanguo_data.datawriter._save_to_vnpy_db", lambda bars, cfg: called.setdefault("bars", bars))
+    write_daily("600000", df, cfg)
+    assert (tmp_path / "daily" / "2026" / "600000.parquet").exists()
+    assert len(called["bars"]) == 1