According to observed data at Banghu and Xiushui hydrologic stations, this paper in combination with topography of the lake region analyzes water exchange between Banghu Lake and Poyang Lake.On the basis of the prediction results of impacts of the Three-Gorges Project on water level at Xiushui, Xingzi and Duchang hydrologic stations in Poyang Lake, the authors analyzes the impacts of the Three-Gorges Project on water regime of Banghu Lake in detail.