Owing to the impacts of urbanization and climate change,urban floods become more and more serious,which is one of the urgent problems to be solved.Therefore,it is necessary to conduct flood inundation modeling and risk assessment in urban area.A coupled model on basis of SWMM has been proposed for predicting urban flooding in Fengxi New town,Xian.This model was used to simulate the process of urban flood routing and assess the corresponding flood risk under various rainstorm scenarios of different return periods with the duration of 2 hours and the rain peek coefficient of 0.4,which were designed by the rainstorm intensity formula and the Chicago rainfall hydrograph.These results show:the designed drainage network in the study area can withstand the rainstorm with a 3-year return occurrence,but for the rainstorm whose return period is higher than this frequency,different degrees of waterlogging would occur;the node with the most serious overflowing would have the maximum ponding depth of 0.20 m for the rainstorm with the frequency of T = 10a,and it would cause a little influence on the city management.This node would have the maximum ponding depth of 0.56 m for the rainstorm with the frequency of T = 20a,which would lead to severe urban flood disaster.According to the ponding water depth obtained from the simulation results,the evacuation information needs to be issued timely in the case of the rainstorm with the frequency of T = 20a,and the ponding water can lead to instability of pedestrians and vehicles around the overflowing node with a 10 m radius during the rain period from 75 to 105 min.