diff --git a/docs/design_docs/segcore/Search.md b/docs/design_docs/segcore/Search.md
index 503f9cf3b7..4ef47b526d 100644
--- a/docs/design_docs/segcore/Search.md
+++ b/docs/design_docs/segcore/Search.md
@@ -6,7 +6,7 @@ update: 9.16.2021, by [xiaofan-luan](https://github.com/xiaofan-luan)
 
 ## Search
 
-Search now supports two modes: json DSL mode and Boolean Expr mode. We will talk about the latter one in details because the former has been deprecated and is only used in test.
+Search now supports two modes: json DSL mode and Boolean Expr mode. We will talk about the latter one in detail because the former has been deprecated and is only used in test.
 
 The execution mode of Boolean Expr works as follows: