Taking a development zone in Zhongshan City as an example, taking the total cost of gray-green infrastructure, runoff coefficient and total node overflow as the objective function, and taking the waterlogging risk level of sub catchment area as the penalty function, a multi-objective optimization model of gray-green coupling drainage system was constructed.Based on NSGA-II algorithm, the SWMM interface program was compiled, and the SWMM was constructed to calculate the rain flood model and optimize the scheme. The scale of gray storage facilities and green LID facilities under 24h design rainstorm conditions was optimized and comprehensively evaluated.The results show that the runoff coefficient and the reduction of total node overflow decrease linearly with the increase of the cost of green LID facilities, and accelerate with the increase of the return period.There is an obvious inflexion point in the curve between the volume of storage facilities and the total node overflow, and the marginal benefit of the scale increase after the inflexion point tends to zero.The proposed grey-green coupling infrastructure optimization model and solution program have low technical requirements for initial population setting and can converge stably, providing support and basis for the formulation of urban stormwater management scheme.