Abstract: With the running of Three Gorges Project and other hy draulic engineerings on the main stream of Yangtze River, the cumulative effect of hydraulic engineering construction on wetland systems of Dongting Lake and P oyang Lake are more and more obvious. It has mainly manifested as the influences of sediment accumulation on wetland succession and hydrology changing on biolog y and biological environment. It is the same to the influence on two lake wetlan d inhabitants, but the influence on the succession is very different: for Dongti ng Lake, The hydraulic engineering complexes on upper main stream of Yangtze Riv er decelerate positive succession, but the degree of atrophy will be deteriorate d; for Poyang Lake, those constructions will destroy dynamically balanced proces s of sediment and great accelerate its positive succession.