diff --git a/docs/en/concepts-and-designs/oal.md b/docs/en/concepts-and-designs/oal.md
index af618b6ef07be4e513fb6d93baf61533c92b1112..4844d07a6ce04687c2f84fd4028c645ba0f611ef 100644
--- a/docs/en/concepts-and-designs/oal.md
+++ b/docs/en/concepts-and-designs/oal.md
@@ -130,7 +130,7 @@ endpoint_rpc_calls_sum = from(Endpoint.*).filter(type in [RequestType.RPC, Reque
 endpoint_url_sum = from(Endpoint.*).filter(endpointName in ["/v1", "/v2"]).sum()
 
 // Calculate the sum of calls for each service.
-endpoint_calls = from(Endpoint.*).sum()
+endpoint_calls = from(Endpoint.*).count()
 
 // Calculate the CPM with the GET method for each service.The value is made up with `tagKey:tagValue`.
 service_cpm_http_get = from(Service.*).filter(tags contain "http.method:GET").cpm()