Introduced and summavized the representative research methods and results for the frequent extreme low water level problem of the Poyang Lake in recent years,through the aspects of the River-Lake relations among the Poyang Lake,Yangtz River and Five Rivers, revealing that the Three Gorges Dam and the extensive activity of coping down are important reasons of the trends of Poyang Lake’s conditions of water and sediment, and may cause the pollution of the lake’s environment get worse, providing a certain direction of solving the wetland degradation problem.