To do this properly you have two options
(1) Get a local distributor to buy it from you in foreign currency. They will pay out outside China, you will sell it to them outside China, and they will handle all the importing and tax issues themselves.
(2) Sell directly to your end customers. Again, you sell it to them outside China, they pay you outside China, and they handle the importing and taxes themselves.
In either case, if you are in China most of the time and selling the stuff, you are technically required to set up a Rep Office to be your official presence here. If you are only visiting occasionally to do the selling you can just do it on a business visa.
In either case, but especially in case (1), be VERY careful about what your distributor is doing, how they are representing the products, how they are selling them, etc. Assume they are in it for a quick profit, and care nothing for your product or brand. The scams, misrepresentations, bad service, and etc. done by the local distributors or agents in China have ruined many foreign brands.
Good luck.
