Floodplain is natural area that sometimes can be flooded because the increase of river’s water surface. This condition makes the residential areas of this place have a high vulnerable level to flooded, as found in residential areas around Winongo River. The purpose of this study is to create a model of the flood inundation in Winongo River and to determine the numbers of area and building that most impacted with various flow scenario. The modeling of the flood inundation used Geographic Information System (GIS) software. This study used several software, ArcMAP for processing of spasial data, HEC-RAS for hydraulic analysis, and ArcGis Pro for visualization the result of analysis and buildings in three dimensions. The flow scenario is use in the analysis are 2, 10, and 25 years return period steady flow. The result analysis of Q2 showed the area that most impacted is Bantul Regency, 118,97 ha, 561 buildings, Q10 showed the area that most impacted is Bantul Regency, 180,5 ha, 885 buildings, and Q25 showed the area that most impacted is Bantul Regency, 206,6 ha, 1.048 buildings.