what means of transport that i can take from the shanghai airport to Yiwu city, how much does it cost

Actually, there are two airports in Shanghai. If you mean Pudong Airport, direct long-distance buses run for the journey. It costs CNY180/person.

If you mean Hongqiao Airport, walk to Honqgiao Railway Station upon yout landing. At the train station, there are many high-speed trains to take you to YW within around 2.5h. The train fare is CNY89.5 for a second class seat and CNY107.5 for a first class seat.

For the back journey, you can use the same way.