[Objective] The model to optimize design of sponge city residential areas was established in order to provide beneficial support for the stormwater system design and construction such sponge city residential areas. [Methods] Based on discussions of outflow runoff coefficient, runoff pollution, and sponge facilities, and taking the minimum annual cost and maximum runoff pollution reduction rate as objective functions, a bilevel coupling optimization model of sponge city residential areas was established by nonlinear programming. Model validity was analyzed and verified by taking sponge city construction areas in a region of Hefei City as a case study. [Results] After optimization, the outflow runoff coefficients in communities A, B, and C were 0.257, 0.268, and 0.303, respectively. The total cost was 1.11×10⁷ yuan, and the annual cost was 9.87×10⁵ yuan. The runoff pollution removal rate was 70.06%, which significantly improved the economic and environmental benefits compared with the original design scheme. [Conclusion] The application of the bilevel coupling optimization model in the design of sponge city residential areas can effectively reduce the annual cost, increase the reduction rate of runoff pollution, and make sponge city design and construction more reasonable.