According to preliminary statistics, there are 9.4×106ha of mire, 8.0×106ha of lake, 2.1×106ha of salt marsh, 2.7×107ha of shallow sea (0-5m), and 3.8×107ha of paddyfield, their total area amounts to 8.45 ×107ha. Wetland consists of natural wetland system and man-made wetland system. According to hydrology, landform,soil and vegetation etc., natural wetland can be divided into the following types: marine, esturine, riverine, lacustrine,palustrine subsystems. On the basis of the wetland bottom compound, waterlogged state and vegetation forms, it can be subdivided into 2 wetland classes. Man-made wetland can be subdivided into 4 wetland classes. Wetland is a unique landscape in the earth and one of the most important living environment with rich resources and many functions. At present, 22 different types of Wetland Natural Reserves have been established in China, in which 7 Wetland Nature Reserves have been listed in international important wetlands of "The Wetland Convention".