Abstract: Objective Urban storm floods cause dramatically property damage and severely influence on city life.It is an emergency issue and a knotty problem to be solved.Much research focuses on raster-basedDEM and hydrodynamic equations to simulate inundation processes.Nevertheless,current methodsstrictly require hydrology data and are unable to model accurately the urban terrain features.By em-ploying a constrainted Delaunay triangular irregular network(CD-TIN),complex urban surfaces areprecisely modeled in detail.Urban basins,serving as simulation units,are generated based on the wa-ter flow rules for triangular surface.Referring to the capacity of the drainage and complexity of urbanterrain features,we introduce the basin runoff yield and confluence method for spatio-temporal calcu-lation step by step.In order to obtain the inundated extent and water depth,a numerical solution isput forward based on the concept of triangular-prism sets through dichotomy.The main campus ofBeijing Normal University(BNU)is used as a case to construct the CD-TIN and to simulate the“7.21storm”inundation event,2012,to test the usability and suitability of the method presented.Simula-tion water depths are compared with the observation data,showing that the CD-TIN based method forurban inundation simulation is effective and reliable.The CD-TIN based simulation method will beuseful for urban flood emergency preparation,storm flood risk analysis and urban reforms in potentialinundation areas.