i want to visit PRC for starting a business.My sister is studying in PRC.She holds X1 type.

Kazim, if so, you can apply for an S type to enter PRC.
Firstly, prepare these materials: your passport and copy of its data page, the application form, a passport-sized color photo taken recently, an invitation letter from a duly authorized unit, an invitation letter from your sister and copies of her passport and residence permit, relationship proof, and medical report. Secondly, submit the application to the embassy of PRC to apply for it.
After you enter PRC with S type, you can try to start your business there, and then you can change S type to work Z type to do the business there.

Thanks for ur reply sir.What is letter from duly authorized unit.How can i get this?

Kazim, it is also an invitation letter, but it should be issued by an authorized unit in PRC, such as Chinese tourist bureau.
You can find a travel agency to get the invitation for you.