diff --git a/store/zhihu/_store_impl.py b/store/zhihu/_store_impl.py
index cd01552..6d029a4 100644
--- a/store/zhihu/_store_impl.py
+++ b/store/zhihu/_store_impl.py
@@ -113,6 +113,8 @@ class ZhihuDbStoreImplement(AbstractStore):
                     if hasattr(existing_content, key):
                         setattr(existing_content, key, value)
             else:
+                if "add_ts" not in content_item:
+                    content_item["add_ts"] = utils.get_current_timestamp()
                 new_content = ZhihuContent(**content_item)
                 session.add(new_content)
             await session.commit()
@@ -133,6 +135,8 @@ class ZhihuDbStoreImplement(AbstractStore):
                     if hasattr(existing_comment, key):
                         setattr(existing_comment, key, value)
             else:
+                if "add_ts" not in comment_item:
+                    comment_item["add_ts"] = utils.get_current_timestamp()
                 new_comment = ZhihuComment(**comment_item)
                 session.add(new_comment)
             await session.commit()
@@ -153,6 +157,8 @@ class ZhihuDbStoreImplement(AbstractStore):
                     if hasattr(existing_creator, key):
                         setattr(existing_creator, key, value)
             else:
+                if "add_ts" not in creator:
+                    creator["add_ts"] = utils.get_current_timestamp()
                 new_creator = ZhihuCreator(**creator)
                 session.add(new_creator)
             await session.commit()