Abstract: From September 7 to 8, 2023, a record breaking extremely heavy rainstorm occurred in Shenzhen City, breaking seven historical extremes since 1952 when there was a meteorological record in Shenzhen. Among them, the 3 hour rainfall in Ailian River area, the center of rainstorm in Longgang District, exceeded the 100 year return period, leading to serious urban waterlogging. Taking the Ailian River area of Longgang District as an example, this paper constructs a coupled model of urban rainstorm and flood, simulates the flood situation of the "9·7" extremely heavy rainstorm in Shenzhen in 2023, analyzes the flooding situation in the central downtown of Longgang, and provides a basis for revealing the causes of flood disasters and proposing prevention and control measures.