Abstract: Jinan has experienced rapid urbanization in recent decades, and extreme rainfall over this city becomes increasingly more frequent, often resulting in serious urban flooding. In this study, the Infoworks ICM (Integrated Catchment Modeling) was used to construct a storm water network model for the Xinglong sponge city pilot area, and its flood inundation was simulated for scenarios of different rainfalls. Distribution of inundation nodes and overload pipes in extreme rainfall events were detected to analyze the cause of flood inundation. The simulations show a good agreement with the observed data. The results show that rainfall intensity was a significant factor in flood events: to determine whether or not a flood happens and how intense of the flood, and that the existing capability of some drainage networks is insufficient. This study has revealed the flow process of pipe networks in a rainstorm event and its mechanism in generating inundation and assessed the capability of drainage networks, thus providing a useful support to the design and construction of sponge city areas.