diff --git a/docs/design_docs/datanode_recovery_design_0513_2021.md b/docs/design_docs/datanode_recovery_design_0513_2021.md
index 78e39617dd..7ae96c16d0 100644
--- a/docs/design_docs/datanode_recovery_design_0513_2021.md
+++ b/docs/design_docs/datanode_recovery_design_0513_2021.md
@@ -6,7 +6,7 @@ update: 6.21.2021, by [Goose](https://github.com/XuanYang-cn)
 
 ## What's DataNode?
 
-DataNode processes insert data and persist them.
+DataNode processes insert data and persist insert data into storage.
 
 DataNode is based on flowgraph; each flowgraph cares about only one vchannel. There are data definition language (DDL) messages, data manipulation language (DML)
 messages, and timetick messages inside one vchannel, FIFO log stream.