Abstract: With the continuous development of sponge city construction, accurately assessing the effect of sponge city construction attracts a lot of attention recently. Although a national standard titled Assessment Standard for Sponge City Construction Effect has been published, there is a lack of systematic monitoring data, practical cases and relevant experience for quantitative assessment. Therefore, taking west catchment of Baguang in Shenzhen as the study area, online flowmeters were installed at the rainwater outlets of source control projects and a typical catchment to quantitatively assess the runoff control effect of sponge city facilities at both project and catchment scale. Based on SWMM(Storm Water Management Model), the study area model was constructed, and the model parameters were calibrated with monitoring data. The overall effect of sponge city construction in the study area was evaluated by multi-scenario simulation. The results show that source control projects and typical catchment meet the requirements of runoff volume control. Through the construction of sponge city, the total amount of regional runoff, peak flow and waterlogging have been effectively controlled. The above research results can provide reference for parameter selection and construction effect evaluation of coastal sponge city model.