how i travel from hong kong to ningbo with train?

There is no direct trains between and it is suggested to make a transfer in Guangzhou.
It is suggested to take the trains from Hung Hom, HK to Guangzhou East Railway Station.
Then you can go to the Railway Station by GZ local public subway systems. From local Railway Station, you can find the only one train K210/K211 to NB directly. This train costs about 23 to 24 hours.