Urban　flood　disasters　have　occurred　frequently　worldwide　in　recent　years,　causing　huge　population　and　property　damages.　Dynamic　and　accurate　assessment　of　the　occurrence　and　development　of　urban　flood　damages　is　the　foundation　for　comprehensively　understanding　flood　risks　and　formulating　flood　relief　measures.　This　study　proposes　a　dynamic　flood　damages　assessment　model,　which　achieves　dynamic　evaluation　of　flood　damages　under　different　relief　measures　by　improving　the　function　expression　of　the　S-curve.　The　model　depicts　the　functional　relationship　between　disaster　damage　and　the　flood　process,　and　simulates　the　effects　of　implementing　different　disaster　relief　measures　at　different　time　on　the　process　of　disaster　damage.　Three　relief　measures　were　considered　to　quantify　the　disparities　in　disaster　damage:　termination　type　(which　directly　stops　the　growth　of　disaster　damages),　decay　type　(which　induces　damage　curve　enter　the　decay　stage),　and　weakening　type　(which　causes　the　rate　of　increase　in　flood　damage　decreases).　The　disaster　evolution　pathways　were　analyzed　to　demonstrate　damages　in　the　urban　flood　disaster　chains,　such　as　the　submergence　events　of　the　subway　line　5　and　the　Jingguang　Expressway　tunnel.　The　research　findings　show　that:　(1)　By　using　actual　damage　data　and　points　of　interest　(POIs)　data,　the　model　demonstrated　a　good　fit　with　Nash-Sutcliffe　efficiency　coefficient　(NSE)　＞　0.837.　(2)　The　timeliness　and　intensity　of　disaster　relief　measures　are　crucial　factors　in　reducing　disaster　losses.　In　the　two　disaster　events,　timely　disaster　relief　measures　reduced　disaster　damages　by　52.2　%　and　30.6　%,　respectively,　comparing　to　untimely　measures.　(3)　The　urban　flood　disaster　assessment　model　requires　some　application　conditions,　including　the　concentrated　regional　rainfall,　flat　terrain,　and　a　substantial　number　of　data　points.