This Study is about the wetlands in the GyunggiDo Mountains. It is written in the point of the hydrogeomorphology, geology, and soil. And it has accessed to ecological environment. Wetlands are divided into mountain wetlands and river wetlands by location, relief, processes, hydrology, and the type of inlet and outlet of water in wetlands. Mostly mountain wetlands are formed by the process of destruction of mountain slope. So they are to be located in the knickpoint. Therefore the underground surface is visible and underground water is rising or leaking. At this process, the environment forming wetlands are made by soil that was influenced by geology and composed by fine and very fine granules.