Abstract: Taking 3×50% motor-driven feed water pumps of CPR1000 nuclear power station as research object, and using CPR1000 digital control system simulation platform based on RELAP5 and Simulink codes, the best estimate calculation of effects on reactor operation caused by single or double failures of feed water pump and corresponding mitigation measures were performed. The results show that the effect on reactor operation caused by single failure of feed water pump is small, and the relevant parameters can quickly return to the steady-state condition before the accident. In the case of double faults of feed water pump: When the initial nuclear power is equal or less than 75%FP, the steam generator (SG) will not reach low-low level; when the initial nuclear power is above 75%FP, and the initial turbine load is equal or less than 90%FP, turbine load need step down to 50%FP to avoid SG low-low level; when the initial turbine load is above 90%FP, shutdown of the reactor is proposed.