///Determining flood inundation area is core of flood damage assessment and flood control decision. Using ArcMap tool, natural flood prevention capacity of the analysis region is classified by non-source flood analysis method based on TIN data. The flood inundation area is extracted and statistical calculated with given water level condition, and the relation formula of flood level elevation and inundation area is also established, which is applied to flood inundation rapid prediction. 3D simulation of non-source flood progressive inundation considering raising flood level is provided.