my study is sept15 to July16. I want to go there on 1July15 back 31 Aug16. what visa do I get?

Iun, you should apply for a L type for your visit. However, if you already have your X type before you go to China on July 1, then you'd better cancel your trip. If you try to apply for L type at that moment, your X type will be void.

According to what you said, your study peroid is around 10 months. In this case, you should apply for X1 type. If your school allows you to register your study in advance, then you may enter with your X1 type and immediately change it to a temporary resident permit within 30 days.