diff --git a/docs/design_docs/segcore/timetravel.md b/docs/design_docs/segcore/timetravel.md
index da75b01509..9bbda7955f 100644
--- a/docs/design_docs/segcore/timetravel.md
+++ b/docs/design_docs/segcore/timetravel.md
@@ -14,8 +14,8 @@ Currently，There are two paths to implement time travel:
 
 1. During load, data is placed in a continuous memory area named chunk, with following properties:
    1. Data is divided into multiple segments
-   2. The data in one segment is ordered by primary key
-   3. Data between Segment is in timestamp order. Namely that the ts of any entity of the previous segment must be less than the timestamp of the first entity in next segment
+   2. Data in one segment is ordered by primary key
+   3. Data between Segments is in timestamp order. That is, the ts of any entity of the previous segment must be less than the timestamp of the first entity in next segment
 
 2. The Algorithm for time travel is 
    1. Use get_active_count interface, find the last segment containing a legal ts, and return the last element position of this segment as vec_count