Hello, Mahmoud, when will you arrive in Shanghai? There are many trains between Shanghai and Yiwu, say D-prefaced trains, Through Trains, Express Trains, etc. Some of them departs from Shanghai Railway Station, others will departs from Shanghai South Railway Station. Generally,it will take about 2 and half hours by the D-prefaced trains with the cost about CNY116.00 net for the first class, CNY97.00 net for the second class, but it will take 3 and half hours or so or near 4 hours for the other types with the cost about CNY72.00 net for the soft seat. You can book it from the hotel or buy it directly when you are at the airport. Good luck!