i want to work in china. i do not know any person & company.

Dear, if you don't know any person or company in PRC, you can't apply for the work Z type visa. I know, you want to enter first and then find a job there, but it's almost impossible because you can find no one to help to gain an M type or F type entry permit. For the tourist L type entry permit, you can only get it through a travel agency and you need to travel in a tour group.