I have 1 year multi visa for China .

Javad, if you don’t have residence permit in PRC, I’m afraid it’s not easy for you to get HK entry permit from there. You’d better apply for it in your home country.
If you want to apply for a tourist entry permit for HK, you need to provide these documents first: copy of your passport, the application form, a passport-style photo, proof of your financial support, as well as hotel reservation and transportation arrangement, and your travel itinerary.
Afterwards, go to the embassy of PRC to submit the application.