diff --git a/README.md b/README.md
index c5e25e3..af71afa 100644
--- a/README.md
+++ b/README.md
@@ -73,8 +73,10 @@ tail -f /tmp/sz-server.log        # 实时看
 
 ```
 data/
-  ├─ app.db              SQLite (transfers / files / chunks)
-  ├─ storage/日期/任务ID/  密文卷目录 (chunk_0001..N, 不合并)
+  ├─ app.db              SQLite (users / transfers / files / chunks)
+  ├─ storage/用户名/日期/任务ID/  密文卷目录 (每用户独立目录, chunk_0001..N, 不合并)
+  │    admin/    SZ_TOKEN 上传的文件
+  │    用户名/   注册用户上传的文件
   └─ tmp/任务ID/          上传中的卷 (complete 后 move 入 storage)
 ```
 
diff --git a/api.py b/api.py
index 043cd0d..55d51cd 100644
--- a/api.py
+++ b/api.py
@@ -250,7 +250,7 @@ async def complete(transfer_id: str, request: Request, username: str = Depends(v
                 "error": f"缺卷: {transfer['chunk_count'] - len(got)} 卷未上传",
             })
         tasks.set_status(transfer_id, "storing")
-        final_dir = storage.store_chunks(transfer_id, TMP_ROOT / transfer_id)
+        final_dir = storage.store_chunks(transfer_id, TMP_ROOT / transfer_id, username)
         file_id = db.insert_file(
             transfer_id,
             transfer["file_name"],
diff --git a/storage.py b/storage.py
index 1016237..02d0320 100644
--- a/storage.py
+++ b/storage.py
@@ -20,12 +20,14 @@ class Storage:
         self.tasks = tasks
         self.storage_root = Path(storage_root)
 
-    def store_chunks(self, transfer_id: str, chunk_dir: Path) -> Path:
-        """卷目录 -> 最终存储目录 (整体 move, 返回目标目录路径)
+    def store_chunks(self, transfer_id: str, chunk_dir: Path, user_id: str) -> Path:
+        """卷目录 -> 用户目录/日期/transfer_id (整体 move, 返回目标目录路径)
 
+        每用户独立目录 (user_id 已过注册校验: 3-32 位字母数字/下划线, 无路径风险)。
         注意: 目标目录不能预创建, 否则 shutil.move 会嵌套成 dst/dst/。
         """
-        day_dir = self.storage_root / datetime.now().strftime("%Y-%m-%d")
+        user_dir = self.storage_root / user_id
+        day_dir = user_dir / datetime.now().strftime("%Y-%m-%d")
         final_dir = day_dir / transfer_id
         if final_dir.exists():
             raise OSError(f"存储目录已存在: {final_dir}")
diff --git a/tests/test_api.py b/tests/test_api.py
index 4ff9a8d..860b241 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -117,6 +117,8 @@ class ServerPipelineTest(unittest.TestCase):
         self.assertIsNotNone(row)
         chunk_dir = Path(row["path"])
         self.assertTrue(chunk_dir.is_dir())
+        # 每用户独立目录: admin 上传 -> storage/admin/日期/transfer_id
+        self.assertIn("admin", chunk_dir.parts)
         chunk_files_on_disk = sorted(chunk_dir.glob("chunk_*"))
         self.assertEqual(len(chunk_files_on_disk), len(chunk_files))
         # 卷内容与客户端上传的卷一致