Abstract: Comprehensively considering the cost and security constraints of nuclear power participating in peak load regulation,an optimization model for combined multi regulating sources of thermal power,pumped storage power and especially nuclear power is established.The peak regulation cost of pressurized-water reactor（PWR） nuclear power plant is quantitatively analyzed from the perspective of economy and security with the nuclear safety value coefficient for coordination and balance.The optimal objective is set to minimize the total fee of joint operation.Based on the normal constraints of optimal scheduling,the time coupling constraints with consideration of the peak regulation depth and the linear power change rate are set to meet the requirement of safety operation.Simulation results verify the validity of the model; nuclear power units meet the requirements of safety constraint and both the peak regulation depth and the power change rate can be optimized according to actual situation of power system; peak regulation pressure of regular power units is released and the start-up and shut-down frequency of thermal power is reduced with participation of nuclear power,improving the safety and economy of power system operation.