I'm scared if I book the ticket and after that they will not give me the visa

Ayman, if you apply for the tourist L type and you don't have an invitation letter from China, you have to submit the ticket booking when doing the application. So it's better to book refundable tickets. In case that your application is denied, you can get the refunds.

Yes, but I fill M type (multiple) I booked ticket and the hotel, and I don't have invitation letter.. The tickets are not refundable...

If you apply for business M type, the round trip air tickets are not required; but if you don’t have the invitation letter, you can only apply for tourist L type.

Ok how can I get the visa where can I enter the country multiple times?

If you want to enter PRC for multiple times, you should apply for am M or L type with multiple entries. So you will apply for L type, right? If yes, you should first prepare the required documents including your passport and copy of its data page, the filled-out application form affixed with a passport-sized color photo taken recently, as well as round trip air tickets and hotel reservation. And then submit your application to the CVASC to apply for it.