By plane:
Usually there are three flights each at 09:30, 11:40, and 21:40. It takes around 2 hours.

buy train:

4 trains from Guangzhou to Yiwu as below:

Train No.
 Dep Station-Arr Station
 Dep Time-Arr Time
 Runtime
 Price
 
T170
 Guangzhou-Yiwu
 13:58 - 05:39
 15hrs41mins
 Hard seat 179 hard sleeper with lower berth 327
 
K528
 Guangzhou-Yiwu
 08:02 - 01:01
 16hrs59mins
 Hard seat 179 hard sleeper with lower berth 327
 
K210/K211
 Guangzhou-Yiwu
 15:08 - 08:39
 17hrs31mins
 Hard seat 179 hard sleeper with lower berth 327
 
K512
 Guangzhou-Yiwu
 08:57 - 02:06
 17hrs9mins
 Hard seat 179 hard sleeper with lower berth