Poyang Lake is the largest fresh-water lake in China, which is formed by the swallowing and spiting of Yangtze River water, and so is called the natural regulator of Yangtze River water level. As a special wetland ecosystem, Poyang Lake is rich with various wetland effects. The main ecological functions of Poyang Lake include storing water; regulating river level; adjusting climate; purifying water, soil and air; fixing C and releasing O_2; controlling erosion; protecting soil; nutrition circling; being habitats. The direct products include supplying water, producing plant, animal and energy; water transporting; being research and education site; the lake is directly the entertainment/tourism place. Poyang Lake wetland ecosystem has biodiversity and social importance.