Abstract: LID facilities play an important role in regulating extreme rainfall, resisting flood disasters, and improving the construction of "sponge cities". However, their design often ignores the ecosystem environmental benefits of LID facilities, and there is a lack of evaluation methods for the comprehensive benefits of facilities. Realizing the layout and optimization of LID facilities at small and medium scales and incorporating various added values of LID facilities into the comprehensive evaluation system has become one of the research hotspots in this field. Taking a built-up community in Beijing as an example, this paper constructs a stormwater management model for the study area using data such as the terrain and rainwater pipe network of the community. At the same time, the benefits of LID facilities on stormwater reduction are evaluated, that is, the ecosystem service value brought by the facilities is evaluated through a monetization method, including the initial investment cost, maintenance cost and ecosystem service value provided by the facilities during their life cycle, and the discount is performed. The stormwater management model is combined with the benefit evaluation to form a coupled optimization model. Considering the growth potential of maintenance cost and ecosystem service value of LID facilities during their life cycle, the spatial layout of LID facilities was optimized by non-dominated sorting genetic algorithm (NSGA-Ⅱ). The facility area was used as the decision variable, and the runoff reduction rate and net cost were used as the objective function. The entropy weight-TOPSIS method was used to comprehensively evaluate and optimize the laying scheme. Under the premise of meeting the relevant constraints, a runoff reduction rate of 76.3% was achieved, and the comprehensive net cost was 1.4×10⁶ yuan. This study aims to provide a more comprehensive decision-making basis for sponge city construction, promote the reuse of water resources and the improvement of urban environment, and provide important urban ecological support and emission reduction channels for achieving carbon peak and carbon neutrality goals by evaluating the comprehensive benefits of LID facilities. The algorithm and the monetization results of the added value of the facilities in this study have a certain degree of universality. After appropriate adjustment of the parameters according to the actual engineering, they can be applied to other study areas, providing a reference for the optimization of the layout of LID in these areas.