diff --git a/backend/backfill_agg_trades.py b/backend/backfill_agg_trades.py
new file mode 100644
index 0000000..0be8463
--- /dev/null
+++ b/backend/backfill_agg_trades.py
@@ -0,0 +1,348 @@
+"""
+backfill_agg_trades.py — 历史aggTrades回补脚本
+
+功能：
+  - 从当前DB最早agg_id向历史方向回补
+  - Binance REST API分页拉取，每次1000条
+  - INSERT OR IGNORE写入按月分表
+  - 断点续传：记录进度到agg_trades_meta
+  - 速率控制：sleep 200ms/请求，429自动退避
+  - BTC+ETH并行回补
+
+用法：
+  python3 backfill_agg_trades.py [--days 30] [--symbol BTCUSDT]
+"""
+
+import argparse
+import logging
+import os
+import sqlite3
+import sys
+import time
+from datetime import datetime, timezone
+
+import requests
+
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s [%(levelname)s] %(message)s",
+    handlers=[
+        logging.StreamHandler(),
+        logging.FileHandler(os.path.join(os.path.dirname(__file__), "..", "backfill.log")),
+    ],
+)
+logger = logging.getLogger("backfill")
+
+DB_PATH = os.path.join(os.path.dirname(__file__), "..", "arb.db")
+BINANCE_FAPI = "https://fapi.binance.com/fapi/v1"
+HEADERS = {"User-Agent": "Mozilla/5.0 ArbitrageEngine/backfill"}
+BATCH_SIZE = 1000
+SLEEP_MS = 200  # 毫秒/请求
+
+
+# ─── DB helpers ──────────────────────────────────────────────────
+
+def get_conn() -> sqlite3.Connection:
+    conn = sqlite3.connect(DB_PATH, timeout=30)
+    conn.row_factory = sqlite3.Row
+    conn.execute("PRAGMA journal_mode=WAL")
+    conn.execute("PRAGMA synchronous=NORMAL")
+    return conn
+
+
+def table_name(ts_ms: int) -> str:
+    dt = datetime.fromtimestamp(ts_ms / 1000, tz=timezone.utc)
+    return f"agg_trades_{dt.strftime('%Y%m')}"
+
+
+def ensure_table(conn: sqlite3.Connection, tname: str):
+    conn.execute(f"""
+        CREATE TABLE IF NOT EXISTS {tname} (
+            agg_id INTEGER PRIMARY KEY,
+            symbol TEXT NOT NULL,
+            price REAL NOT NULL,
+            qty REAL NOT NULL,
+            time_ms INTEGER NOT NULL,
+            is_buyer_maker INTEGER NOT NULL
+        )
+    """)
+    conn.execute(f"CREATE INDEX IF NOT EXISTS idx_{tname}_symbol_time ON {tname}(symbol, time_ms)")
+
+
+def ensure_meta(conn: sqlite3.Connection):
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS agg_trades_meta (
+            symbol TEXT PRIMARY KEY,
+            last_agg_id INTEGER,
+            last_time_ms INTEGER,
+            earliest_agg_id INTEGER,
+            earliest_time_ms INTEGER
+        )
+    """)
+    # 添加earliest字段（如果旧表没有）
+    try:
+        conn.execute("ALTER TABLE agg_trades_meta ADD COLUMN earliest_agg_id INTEGER")
+        conn.execute("ALTER TABLE agg_trades_meta ADD COLUMN earliest_time_ms INTEGER")
+    except Exception:
+        pass  # 已存在
+
+
+def get_earliest_agg_id(conn: sqlite3.Connection, symbol: str) -> int | None:
+    """查找DB中该symbol的最小agg_id"""
+    # 先查meta表
+    row = conn.execute(
+        "SELECT earliest_agg_id FROM agg_trades_meta WHERE symbol = ?", (symbol,)
+    ).fetchone()
+    if row and row["earliest_agg_id"]:
+        return row["earliest_agg_id"]
+
+    # meta表没有，扫所有月表
+    tables = conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE 'agg_trades_2%'"
+    ).fetchall()
+    min_id = None
+    for t in tables:
+        r = conn.execute(
+            f"SELECT MIN(agg_id) as mid FROM {t['name']} WHERE symbol = ?", (symbol,)
+        ).fetchone()
+        if r and r["mid"] is not None:
+            if min_id is None or r["mid"] < min_id:
+                min_id = r["mid"]
+    return min_id
+
+
+def update_earliest_meta(conn: sqlite3.Connection, symbol: str, agg_id: int, time_ms: int):
+    conn.execute("""
+        INSERT INTO agg_trades_meta (symbol, earliest_agg_id, earliest_time_ms)
+        VALUES (?, ?, ?)
+        ON CONFLICT(symbol) DO UPDATE SET
+            earliest_agg_id = MIN(excluded.earliest_agg_id, COALESCE(agg_trades_meta.earliest_agg_id, excluded.earliest_agg_id)),
+            earliest_time_ms = MIN(excluded.earliest_time_ms, COALESCE(agg_trades_meta.earliest_time_ms, excluded.earliest_time_ms))
+    """, (symbol, agg_id, time_ms))
+    conn.commit()
+
+
+# ─── REST API ────────────────────────────────────────────────────
+
+def fetch_agg_trades(symbol: str, from_id: int | None = None,
+                     start_time: int | None = None, limit: int = 1000) -> list[dict]:
+    """从Binance拉取aggTrades，支持fromId和startTime"""
+    params = {"symbol": symbol, "limit": limit}
+    if from_id is not None:
+        params["fromId"] = from_id
+    elif start_time is not None:
+        params["startTime"] = start_time
+
+    for attempt in range(5):
+        try:
+            r = requests.get(
+                f"{BINANCE_FAPI}/aggTrades",
+                params=params, headers=HEADERS, timeout=15
+            )
+            if r.status_code == 429:
+                wait = min(60 * (2 ** attempt), 300)
+                logger.warning(f"Rate limited (429), waiting {wait}s (attempt {attempt+1})")
+                time.sleep(wait)
+                continue
+            if r.status_code != 200:
+                logger.error(f"HTTP {r.status_code}: {r.text[:200]}")
+                time.sleep(2)
+                continue
+            return r.json()
+        except requests.exceptions.RequestException as e:
+            logger.error(f"Request error: {e}, retrying in {2 ** attempt}s")
+            time.sleep(2 ** attempt)
+    return []
+
+
+def write_batch(conn: sqlite3.Connection, symbol: str, trades: list[dict]) -> int:
+    """批量写入，返回实际插入条数"""
+    inserted = 0
+    tables_seen = set()
+    for t in trades:
+        tname = table_name(t["T"])
+        if tname not in tables_seen:
+            ensure_table(conn, tname)
+            tables_seen.add(tname)
+        try:
+            conn.execute(
+                f"INSERT OR IGNORE INTO {tname} (agg_id, symbol, price, qty, time_ms, is_buyer_maker) "
+                f"VALUES (?, ?, ?, ?, ?, ?)",
+                (t["a"], symbol, float(t["p"]), float(t["q"]), t["T"], 1 if t["m"] else 0)
+            )
+            inserted += 1
+        except sqlite3.IntegrityError:
+            pass
+    conn.commit()
+    return inserted
+
+
+# ─── 主逻辑 ──────────────────────────────────────────────────────
+
+def backfill_symbol(symbol: str, target_days: int | None = None):
+    """回补单个symbol的历史数据"""
+    conn = get_conn()
+    ensure_meta(conn)
+
+    earliest = get_earliest_agg_id(conn, symbol)
+    if earliest is None:
+        logger.info(f"[{symbol}] DB无数据，从最新开始拉最近的数据确定起点")
+        trades = fetch_agg_trades(symbol, limit=1)
+        if not trades:
+            logger.error(f"[{symbol}] 无法获取起始数据")
+            return
+        earliest = trades[0]["a"]
+        logger.info(f"[{symbol}] 当前最新agg_id: {earliest}")
+
+    # 计算目标：往前补到多少天前
+    if target_days:
+        target_ts = int((time.time() - target_days * 86400) * 1000)
+    else:
+        target_ts = 0  # 拉到最早
+
+    logger.info(f"[{symbol}] 开始回补，当前最早agg_id={earliest}")
+    if target_days:
+        target_dt = datetime.fromtimestamp(target_ts / 1000, tz=timezone.utc)
+        logger.info(f"[{symbol}] 目标：回补到 {target_dt.strftime('%Y-%m-%d')} ({target_days}天前)")
+
+    total_inserted = 0
+    total_requests = 0
+    rate_limit_hits = 0
+    current_from_id = earliest
+
+    while True:
+        # 从current_from_id向前拉：先拉current_from_id - BATCH_SIZE*2的位置
+        # Binance fromId是从该id开始正向拉，所以我们用endTime方式
+        # 更可靠：用fromId = current_from_id - BATCH_SIZE，然后正向拉
+        fetch_from = max(0, current_from_id - BATCH_SIZE)
+
+        trades = fetch_agg_trades(symbol, from_id=fetch_from, limit=BATCH_SIZE)
+        total_requests += 1
+
+        if not trades:
+            logger.info(f"[{symbol}] 无更多数据，回补结束")
+            break
+
+        # 过滤掉已有的（>= earliest的数据实时采集器已覆盖）
+        new_trades = [t for t in trades if t["a"] < current_from_id]
+
+        if not new_trades:
+            # 没有更早的数据了
+            logger.info(f"[{symbol}] 已到达最早数据，回补结束")
+            break
+
+        inserted = write_batch(conn, symbol, new_trades)
+        total_inserted += inserted
+
+        oldest = min(new_trades, key=lambda x: x["a"])
+        oldest_time = datetime.fromtimestamp(oldest["T"] / 1000, tz=timezone.utc)
+        current_from_id = oldest["a"]
+
+        # 更新meta
+        update_earliest_meta(conn, symbol, oldest["a"], oldest["T"])
+
+        # 进度日志（每50批打一次）
+        if total_requests % 50 == 0:
+            logger.info(
+                f"[{symbol}] 进度: {total_inserted:,} 条已插入, "
+                f"当前位置: {oldest_time.strftime('%Y-%m-%d %H:%M')}, "
+                f"agg_id={current_from_id:,}, "
+                f"请求数={total_requests}, 429次数={rate_limit_hits}"
+            )
+
+        # 检查是否到达目标时间
+        if target_ts and oldest["T"] <= target_ts:
+            logger.info(f"[{symbol}] 已达到目标时间，回补结束")
+            break
+
+        time.sleep(SLEEP_MS / 1000)
+
+    conn.close()
+
+    logger.info(
+        f"[{symbol}] 回补完成: "
+        f"总插入={total_inserted:,}, 总请求={total_requests}, "
+        f"429次数={rate_limit_hits}"
+    )
+    return total_inserted, total_requests, rate_limit_hits
+
+
+def check_continuity(symbol: str):
+    """检查agg_id连续性"""
+    conn = get_conn()
+    tables = conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table' AND name LIKE 'agg_trades_2%' ORDER BY name"
+    ).fetchall()
+
+    all_ids = []
+    for t in tables:
+        rows = conn.execute(
+            f"SELECT agg_id FROM {t['name']} WHERE symbol = ? ORDER BY agg_id",
+            (symbol,)
+        ).fetchall()
+        all_ids.extend(r["agg_id"] for r in rows)
+
+    conn.close()
+
+    if not all_ids:
+        logger.info(f"[{symbol}] 无数据")
+        return
+
+    all_ids.sort()
+    gaps = 0
+    gap_ranges = []
+    for i in range(1, len(all_ids)):
+        diff = all_ids[i] - all_ids[i-1]
+        if diff > 1:
+            gaps += 1
+            if len(gap_ranges) < 10:
+                gap_ranges.append((all_ids[i-1], all_ids[i], diff - 1))
+
+    total = len(all_ids)
+    span = all_ids[-1] - all_ids[0] + 1
+    coverage = total / span * 100 if span > 0 else 0
+
+    logger.info(
+        f"[{symbol}] 连续性检查: "
+        f"总条数={total:,}, ID范围={all_ids[0]:,}~{all_ids[-1]:,}, "
+        f"理论条数={span:,}, 覆盖率={coverage:.2f}%, 缺口数={gaps}"
+    )
+    if gap_ranges:
+        for start, end, missing in gap_ranges[:5]:
+            logger.info(f"  缺口: {start} → {end} (缺{missing}条)")
+
+
+# ─── CLI ─────────────────────────────────────────────────────────
+
+def main():
+    parser = argparse.ArgumentParser(description="Backfill aggTrades from Binance")
+    parser.add_argument("--days", type=int, default=None, help="回补天数（默认全量）")
+    parser.add_argument("--symbol", type=str, default=None, help="指定symbol（默认BTC+ETH）")
+    parser.add_argument("--check", action="store_true", help="仅检查连续性")
+    args = parser.parse_args()
+
+    symbols = [args.symbol] if args.symbol else ["BTCUSDT", "ETHUSDT"]
+
+    if args.check:
+        for sym in symbols:
+            check_continuity(sym)
+        return
+
+    logger.info(f"=== 开始回补 === symbols={symbols}, days={args.days or '全量'}")
+
+    for sym in symbols:
+        logger.info(f"--- 回补 {sym} ---")
+        result = backfill_symbol(sym, target_days=args.days)
+        if result:
+            inserted, reqs, limits = result
+            logger.info(f"[{sym}] 结果: 插入{inserted:,}条, {reqs}次请求, {limits}次429")
+
+    logger.info("=== 回补完成，开始连续性检查 ===")
+    for sym in symbols:
+        check_continuity(sym)
+
+    logger.info("=== 全部完成 ===")
+
+
+if __name__ == "__main__":
+    main()