diff --git a/docs/design_docs/segcore/segment_sealed.md b/docs/design_docs/segcore/segment_sealed.md
index 6e06e100af..a0e10ccc0b 100644
--- a/docs/design_docs/segcore/segment_sealed.md
+++ b/docs/design_docs/segcore/segment_sealed.md
@@ -7,8 +7,8 @@ SegmentSealed has an extra interface rather than SegmentInterface:
     3. `VecIndex`: vector index
 2. `LoadFieldData(loadFieldDataInfo)`: load column data, could be either scalar column or vector column
     1. Note: indexes and vector data for the same column may coexist. Indexes are prioritized in search
-3. `DropIndex(fieldId)`: drop and release existed index of specified field
-4. `DropFieldData(fieldId)`: drop and release existed data for specified field
+3. `DropIndex(fieldId)`: drop and release an existing index of a specified field
+4. `DropFieldData(fieldId)`: drop and release existed data for a specified field
 
 Search is executable as long as all the columns involved in the search are loaded.