Loss of power supply can happen at any operating stage of a nuclear power plant, which may be caused by electrical systems failure, offsite power failure, internal hazard, external hazard, etc. Power loss always has an influence on normal operation, which causes a loss or challenge to operating functions, but also adversely affects one or more systems needed to respond to the reactor shutdown, the Fukushima nuclear accident in Japan sounded an alarm bell for us. we must learn from it so that our nuclear power plants can avoid accidents and prevent them in the future. In order to verify power reliability and deal with power loss incidents in time, loss of power supply incident analysis and emergency operating procedure were considered during the design process to reduce the risk. The paper briefly introduces the construction of electrical distribution systems in HPR1000 nuclear power plant (NPP), describes the initial event identification, the analysis scope and the analysis process of the loss of power supply incident firstly, then analyses the management strategy to deal with the loss of power supply, develops a set of operating procedures for the loss of power supply incident eventually, including the verification and the validation, which have been applied in HPR1000 NPP.