China Driving License & HK Driving License

You can get your HK driving license by your China one. You can just go to the Transport Deptment to get it.
Here is some points about the exchanging driving license:
1. You can have your HK 10 years driving licence (Full driving licence )of 1(car) 2(Light Goods Vehicle) types when you have China driving licence of A1(Bus), A2(Articulated Vehicle), B2(Heavy Goods Vehicle, i.e. Truck) types. But the B1(Medium Bus) type may just can get the HK 1(car) type only.
2. You can have your HK 10 years driving licence of 3(Motor Cycle) 22(Motor Tricycle) types when you have China driving licence of D(General Motor Tricycle) E(General Motor Cycle).

You may get more information by the T.D. web site.
http://www.td.gov.hk/public_services/licences_and_permits/vehicle_and_driving_licences/how_to_apply_for_a_driving_licence/index.htm
3.1 Apply for a Full Driving Licence by Direct Issue without Test

I think if he has a certain years of driving licence in China, he is suitable to apply for the relevant HK driving licence. But this is limited to drive private cars and motorcycles. Contact Transport Department for details.