-By fast speed train
1) Following are the departg times of the high speed trains from Hangzhou Railway Station to Yiwu
D193 East Station departing time: 03:50 arriving time: 04:36
D685 East Station departing time: 08:47 arriving time: 09:40
D191 East Station departing time: 10:54 arriving time: 11:40
D95 departing time: 12:37 arriving time: 13:25
D665 departing time: 14:37 arriving time: 15:25
The fast speed train from Hangzhou to Yiwu can't be reserved so you have to buy it when you reach the railway station. Usually, there is no need to book it in advance since you could get the ticket directly from the ticket window.

-By bus:
1)  Between 09:30-21:00(GMT+08:00), I suggest you go to Yiwu by airport bus (RMB60, 100min). Here is the timetable: 10:20, 11:00, 11:40, 12:20, 13:00, 13:40, 14:20, 15:00, 15:40, 16:20, 17:00, 17:40, 18:30, 19:30, 20:30, 21:30.( 40mins/ shift).
2)  During the other time, you can take a taxi (50min, around 100RMB) to Hangzhou train station (or Hangzhou east train station,  according to your time), then take the train.
Or you can also share a taxi (about RMB100) to Yiwu with others, if that's a right time. I mean there is a taxi goes to Yiwu, And there are other people share a taxi with you.So try to arrive at Hangzhou airport between 09:30-21:00(GMT+08:00) if possible.
3)  There are also buses from 07:00 to 19:10 every 15 minutes from Hangzhou South Bus Station to Yiwu Binwang Passenger Transport Center.

-By Private Car:
We could arrange a car to pick you up from the Hangzhou Xiaoshan Airport to Yiwu.