diff --git a/system-variables.md b/system-variables.md
index c6dbe3f5307f8..b9fdbabe39cb4 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -1106,10 +1106,10 @@ mysql> desc select count(distinct a) from test.t;
 
 ### tidb_opt_prefer_range_scan <span class="version-mark">New in v5.0</span>
 
-- Scope: SESSION
+- Scope: SESSION | GLOBAL
 - Default value: `OFF`
-- After you set the value of this variable to `1`, the optimizer always prefers index scans over full table scans.
-- In the following example, before you enable `tidb_opt_prefer_range_scan`, the TiDB optimizer performs a full table scan. After you enable `tidb_opt_prefer_range_scan`, the optimizer selects an index scan.
+- After you set the value of this variable to `ON`, the optimizer always prefers range scans over full table scans.
+- In the following example, before you enable `tidb_opt_prefer_range_scan`, the TiDB optimizer performs a full table scan. After you enable `tidb_opt_prefer_range_scan`, the optimizer selects an index range scan.
 
 ```sql
 explain select * from t where age=5;