I have already visit china in 2007 for import of some toys from shantou china. I want to go again

Dear sir,
I have already visit china in 2007 for import of some toys from shantou china.now i will need visa for to import some generators from china.so please tell me now what is the process of visa.in 2005 a recruiting agency has take me visa of china from china embassy.now they are not doing.