diff --git a/How-to-issue-a-cert.md b/How-to-issue-a-cert.md
index 06c9e52..43b7e92 100644
--- a/How-to-issue-a-cert.md
+++ b/How-to-issue-a-cert.md
@@ -22,7 +22,7 @@ export CF_Key="sdfsdfsdfljlbjkljlkjsdfoiwje"
 
 export CF_Email="xxxx@sss.com"
 
-acme.sh  --issue  -d aa.com  --dns dns-cf
+acme.sh  --issue  -d aa.com  --dns dns_cf
 ```
 
 How to use dns api:  https://github.com/Neilpang/acme.sh/tree/master/dnsapi