diff --git a/system-variables.md b/system-variables.md
index 7c2ba3d92a43a..2a9e594f5cd22 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -944,7 +944,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
 
 ### tidb_memory_usage_alarm_ratio
 
-- Scope: SESSION
+- Scope: INSTANCE
 - Default value: `0.8`
 - TiDB triggers an alarm when the percentage of the memory it takes exceeds a certain threshold. For the detailed usage description of this feature, see [`memory-usage-alarm-ratio`](/tidb-configuration-file.md#memory-usage-alarm-ratio-new-in-v409).
 - You can set the initial value of this variable by configuring [`memory-usage-alarm-ratio`](/tidb-configuration-file.md#memory-usage-alarm-ratio-new-in-v409).