Hello, I'd like to know if there are any options to travel from Yiwu to HK (Kowloon) by CRH.

There is no direct one available, but you can try the route like HK to Guangzhou and then to Yiwu. From HK to GZ, it would be 2 hours and then GZ to Yiwu would be about 7 hours, but still need some time for connection of that 2 trips. The ticket price depends on the seat class etc, maybe like USD150.