A pump start-stops optimization method was proposed to realize the frequent start-stops in rainwater pump station. Through analyzing the design parameters and operation principles, the optimization model of pump start water level was obtained by SWMM(storm water management model) and PSO(particle swarm optimization algorithm). The feasibility of the optimization method was verified by comparing with manual debugging method. The research results show that the optimization method can minimize the start-stop frequency, achieve a better effect of bump start-stops and get rid of the complex manual debugging process, which will provide reference for the pumping water level selection of rainwater pumping stations