With the construction of many hydro-projects in both the trunk stream and tributary the upper reaches of the Yangtze River,especially the Three Gorges Project and the South-to-North Water Diversion Project,and the implementation of converting farmland into forest and grass as well as soil and water conservation,sediment discharge into the sea in the Yangtze River is declining quickly.This reduces the silting rate of the Yangtze River Delta and might degenerate the Yangtze River Delta as well.Formation process of the Yangtze River Delta is discussed,and the impacts of upstream hydro-projects,rising sea level,land subsidence and human activities upon the Yangtze River Delta are analyzed.It is put forward that the coast reclamation which is still being carried on at present is an effective way to prevent the Yangtze River Delta from erosion.The result from the study has some guiding significance to the practice.