Abstract: The electric main feed water pump system of CPR1000 nuclear power plant is responsible for supplying water to the secondary side of the steam generator. Taking two operation events of the main feed water pump system in recent years as the object for study, the reasons for the failure of the standby pump start-up were analyzed, and the corresponding improvement measures were proposed. In view of the design defects of low pressure pump tripping at the pump outlet and interlock starting logic, the functions of self-holding and reset of allowable condition of pump tripping are added. In view of the situation that the reset function of state deviation does not meet the design requirements of operation failure signals, the configuration implementation scheme is improved and the state deviation alarm is added. The improved system interlock start-up scheme was analyzed and verified by the simulator and was popularized and implemented in the CPR1000 unit, which improved the ability of the electric main feed water pump system to deal with complex working conditions, effectively avoided the recurrence of similar events, improved the stability and the safety of the unit operation, and also provided good experience feedback for the optimization and improvement of similar pump sets.