Abstract: In view of the increasingly severe rainstorm and flood problems in cities, to develop an urban-oriented digital twin system was proposed, which integrates "real-time perception, simulation modelling, forecasting and early warning, commanding and decision-making", so as to realize the real-time dynamic monitoring and simulation of all elements on "precipitation, runoff, pipeline network, river network, land surface, gate and pump" in the whole city. Taking the hydrological and hydrodynamic model as the core, with the help of artificial intelligence, big data, cloud computing and other technologies, the digital twin governance system of urban scale flood prevention and drainage will be realized. Thereafter, taking Fuzhou City as the example, the module composition of urban flood digital twin system and its application in flood prevention and drainage is presented.