Abstract: Taishan CEPR Nuclear Power Plant implements the world advanced third nuclear power technology. CEPR nuclear safety futures are specially integrated into the design of electrical power supply systems. The multiple on-site power sources configured in CEPR electrical power supply system indicate the characteristics of redundancy, diversity and separation, and satisfy the principle of Defense-in-Depth. In the design of NI safety power supply systems, the emergency power supply in different levels provide enough power supply under all Design Basic Conditions and Design Extension Conditions, for which they are fully demonstrated by the safety analysis under loss of off-site power supply systems.