This study aim is to establish the suitability analysis of a constructed wetland using Geographic Information System. A constructed wetland is a flood control reservoir that is able to control flows and conserve a preserving integrity of nature maximum. It has been did that DB construction of flood area, socioeconomic analysis, and space analysis using GIS. Achieved reiteration arithmetic function from results of several elements, it has been did analysis for possibility space of constructed wetland. Through the analysis of flood area and a constructed wetland capacity, it has been established the estimation where is possible to build wetland. This study is applied suitability analysis method where has been choose the basin of To-Phyeong river in Kyongsang-namdo with methodology presentation about suitability analysis.