Hi, I am from Iraq, can I visit Macau for 3 days with a single entry visa to mainland China?

Salah, you need to apply for another entry permit when you arrive in Macau. You should have at least MOP 5000, accommodation booking and return air ticket. Then you can apply for the entry permit. It costs MOP 100 to 200. But I can't guarantee that you will apply successfully for sure.

If you don't leave your country, please apply from Chinese embassy for Macau entry permit directly. This is the safest way.