Urban　flood　is　a　serious　challenge　that　increasingly　affects　the　residents.　Simulation　of　urban　flood　is　becoming　increasingly　relevant　in　the　world.　However,　how　to　improve　the　simulation　accuracy　is　still　a　challenge　in　the　field.　This　paper　is　developed　to　propose　a　novel　model　of　SWTM　(SWMM　model　and　TELEMAC-2D　model)　coupling　D8　flow　direction　and　backflow　effect,　improving　the　simulation　accuracy　of　inundation　area,　inundation　depth　and　inundation　duration.　The　model　is　organized　into　three　parts:　one-dimensional　pipe　network　model　establishment,　two-dimensional　surface　inundation　model,　and　coupling　model　SWTM　construction.　The　D8　algorithm　is　introduced　to　subcatchment　division.　The　linear　interpolation　in　DEM　is　applied　to　improve　the　accuracy　of　D8　algorithm.　It　enables　more　accurate　simulation　of　rainfall　runoff　processes　using　the　path　weighted　average　method　for　the　calculation　of　feature　width　and　feature　slope　in　watershed.　The　overflow　and　backflow　effect　of　inspection　wells　are　both　considered　to　simulate　the　flood　inundation　in　the　two-dimensional　surface　inundation　model,　which　can　obtain　the　maximum　inundation　depth　and　inundation　area　more　accurately.　In　the　coupled　model,　the　overflow　and　backflow　process　of　inspection　wells　are　used　as　the　input　condition　of　the　two-dimensional　model　to　simulate　the　flooding　process.　The　new　model　is　applied　to　rainstorm　waterlogging　in　Fangzhuang　area,　Beijing.　It　shows　that　SWTM　model　can　simulate　the　changes　of　inundation　range,　inundation　depth　and　inundation　duration　more　accurately　comparing　with　the　traditional　model.　©　2023