The Reactor Coolant Pumps(RCP) of AP1000 nuclear power plant are the canned motor pump. Because of the restriction of the RCP motor design parameter and operation mode, the Variable Frequency Drive(VFD) shall be used to meet the operation and technical requirements. This paper studies the power supply mode, MV VFD technical and control logic of the RCP, so that the key technology of the AP1000 nuclear power plant can be totally caught and applied to the independent design of the third generation nuclear plants.