I'm Iranian boy, I have an invitation letter from one of the chinese martial art academy but i do not have information about visa and visa form tell me which one application form i need?

You can apply for Business Visa (F visa) by using the invitation letter from one of the Chinese martial art academy. Then the academy has to help you to get the residence permit at the local police station.
You need to fill visa application form V.2011A.

For student visa application, the admission letter and JW201/JW202 are required. The visa application form V.2011A and V.2011B are required to fill in.