diff --git a/backend/app/api/ext_data.py b/backend/app/api/ext_data.py
index a076dd5..92c498d 100644
--- a/backend/app/api/ext_data.py
+++ b/backend/app/api/ext_data.py
@@ -16,6 +16,7 @@ import polars as pl
 from fastapi import APIRouter, File, HTTPException, Query, Request, UploadFile
 from pydantic import BaseModel, Field
 
+from app.market_time import CN_TZ
 from app.services.ext_data import (
     ExtConfig,
     ExtConfigStore,
@@ -255,10 +256,14 @@ def _with_instrument_name(df: pl.DataFrame, data_dir: Path) -> pl.DataFrame:
 
 
 def _latest_sync_date(config: ExtConfig, data_dir: Path) -> str | None:
-    """扫描数据文件，返回该扩展配置的最新同步时间（含时分秒）。
+    """扫描数据文件，返回该扩展配置的最新同步时间（北京墙钟, 含时分秒）。
 
     - snapshot: 直接取 ext_data/{id}/part.parquet 的 mtime
     - timeseries: 扫描 ext_data/{id}/timeseries/date=xxx 分区目录
+
+    用北京时间而非宿主机时钟: 前端 ExtDataStatCard 原样展示这串裸时间,
+    容器默认 UTC 时会比同一页拉取面板里的 pull.last_run(带时区 ISO,
+    浏览器按本地时区渲染)整整差一个时区。
     """
     from datetime import datetime
 
@@ -266,7 +271,7 @@ def _latest_sync_date(config: ExtConfig, data_dir: Path) -> str | None:
         # 快照: part.parquet 与 config.json 同级
         p = data_dir / "ext_data" / config.id / "part.parquet"
         if p.exists():
-            ts = datetime.fromtimestamp(p.stat().st_mtime).strftime("%Y-%m-%d %H:%M:%S")
+            ts = datetime.fromtimestamp(p.stat().st_mtime, tz=CN_TZ).strftime("%Y-%m-%d %H:%M:%S")
             return ts
         # 兼容旧路径
         old = data_dir / "instruments_ext"
@@ -285,7 +290,7 @@ def _latest_sync_date(config: ExtConfig, data_dir: Path) -> str | None:
 
 
 def _latest_sync_from_partitions(base: Path) -> str | None:
-    """从 date=xxx 分区目录中找到最新分区的修改时间。"""
+    """从 date=xxx 分区目录中找到最新分区的修改时间 (北京墙钟)。"""
     from datetime import datetime
     latest_ts: float = 0
     latest_date: str | None = None
@@ -297,7 +302,7 @@ def _latest_sync_from_partitions(base: Path) -> str | None:
                     latest_ts = mtime
                     latest_date = d.name[5:]
     if latest_date and latest_ts > 0:
-        ts = datetime.fromtimestamp(latest_ts).strftime("%H:%M:%S")
+        ts = datetime.fromtimestamp(latest_ts, tz=CN_TZ).strftime("%H:%M:%S")
         return f"{latest_date} {ts}"
     return latest_date
 
diff --git a/backend/tests/test_ext_data_latest_sync_timezone.py b/backend/tests/test_ext_data_latest_sync_timezone.py
new file mode 100644
index 0000000..3b37c7f
--- /dev/null
+++ b/backend/tests/test_ext_data_latest_sync_timezone.py
@@ -0,0 +1,62 @@
+"""扩展数据卡片的「最新」时间必须是北京墙钟, 不随服务端时区漂移。
+
+latest_sync_date 由 parquet 的 mtime 格式化而来, 前端 ExtDataStatCard 原样
+展示这串裸时间。用宿主机时钟格式化, 容器默认 UTC 时同一次同步在卡片上显示
+成 8 小时前, 而同一页拉取面板里的 pull.last_run(带时区的 ISO, 前端按浏览器
+时区渲染)显示的是正确时间 —— 一个页面两个时间对不上。
+"""
+from __future__ import annotations
+
+import os
+import types
+from datetime import datetime
+
+import pytest
+
+from app.api.ext_data import _latest_sync_date
+from app.market_time import CN_TZ
+
+# 固定 epoch 秒 = 北京时间 2026-09-04 22:13:20
+_MTIME = 1_788_531_200
+
+
+def _beijing(fmt: str) -> str:
+    return datetime.fromtimestamp(_MTIME, tz=CN_TZ).strftime(fmt)
+
+
+def _touch(path, mtime: int) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_bytes(b"")
+    os.utime(path, (mtime, mtime))
+
+
+@pytest.fixture
+def snapshot_config():
+    return types.SimpleNamespace(id="ext_gn_ths", mode="snapshot")
+
+
+@pytest.fixture
+def timeseries_config():
+    return types.SimpleNamespace(id="ext_ts_demo", mode="timeseries")
+
+
+def test_snapshot_latest_sync_is_beijing_wall_clock(tmp_path, snapshot_config):
+    _touch(tmp_path / "ext_data" / snapshot_config.id / "part.parquet", _MTIME)
+
+    got = _latest_sync_date(snapshot_config, tmp_path)
+
+    assert got == _beijing("%Y-%m-%d %H:%M:%S")
+
+
+def test_timeseries_latest_sync_is_beijing_wall_clock(tmp_path, timeseries_config):
+    base = tmp_path / "ext_data" / timeseries_config.id / "timeseries"
+    _touch(base / "date=2026-09-03" / "part.parquet", _MTIME - 86400)
+    _touch(base / "date=2026-09-04" / "part.parquet", _MTIME)
+
+    got = _latest_sync_date(timeseries_config, tmp_path)
+
+    assert got == f"2026-09-04 {_beijing('%H:%M:%S')}"
+
+
+def test_latest_sync_is_none_without_any_data(tmp_path, snapshot_config):
+    assert _latest_sync_date(snapshot_config, tmp_path) is None