diff --git a/defs/format_time.py b/defs/format_time.py
index 9f2fe30..7a0e1dc 100644
--- a/defs/format_time.py
+++ b/defs/format_time.py
@@ -5,7 +5,10 @@ date_format = "%Y-%m-%dT%H:%M:%SZ"
 
 def strf_time(data: str) -> str:
     # data = "2021-07-17T09:14:05Z"
-    ts = datetime.strptime(data, date_format)
+    if data:
+        ts = datetime.strptime(data, date_format)
+    else:
+        return "未知"
     # UTC+8
     ts = ts + timedelta(hours=8)
     return ts.strftime("%Y/%m/%d %H:%M:%S")