In order to reveal the response mechanism of water environment change in the Dongting Lake to the water impoundment of the Three Gorges Reservoir, the former research was summarized and analyzed. The main conclusions have been drawn as follows: The main pollutants in the Dongting Lake were still total nitrogen and total phosphorus after the Three Gorges Dam was put into operation. The water quality of the lake has changed from poor-medium to mild eutrophication, which implies that the water quality is further deteriorated; The Three Gorges Project changed the original hydrological rhythm and the bed erosion and deposition in the lake area, which resulted in some changes in water quality indexes; The increasing emissions from the tributaries and Jingjiang reach gradually deteriorated water quality in the Dongting Lake; Lake-bed exposure time was advanced, and the wetland ecosystem suffered some damage to some extent; In addition, there are some differences in the evaluation indexes and results among different scholars, which has a certain impact on the water environment governance. It has been an urgent scientific issue to be solved that the reasonable prediction mechanism of water quality should be established under the operation of the Three Gorges reservoir. The prediction mechanism could provide us with the scientific grounds and theoretical basis for the trend prediction and comprehensive management of water environment in the lake area.