How to completely refuse spam comment!!!

Hello everyone here,
I have a trouble with spam comment, I’m using Disqus comment system plugin to instead the wordpress one. Normally, visitor cannot see the original comment table, they will see Disqus comment system’s table, so human cannot leave any messages to my website. But I still receive different spam comments!! My setting in Discussion is checked “Users must be registered and logged in to comment (Signup has been disabled. Only members of this site can comment.) ” I thought this is work, but it’s not, helllllllllllp! Please.