In accordance with the natural, geographic, and ecological characteristics of the Taihu Lake Basin, and the relation between the water body of Taihu Lake and its surrounding environment, an area, which has tight relevance with the water environment of Taihu Lake, was token as the main investigation region. The area was named as the Taihu Lake Region. Some factors, such as TN, TP, COD_Cr that characterized the main environmental problem, the eutrophication were selected when conducted the pollution sources investigation on in Taihu Lake Region. The categories, distribution, pollution contribution to the Lake of dijferent pollution sources, as well as the routes of pollutants entering the Lake were basically made clear. Pollution sources that must be preferentially controlled and the direction of controlling those main pollutants, such as TN, TP, CODCr, were proposed. Base on the investigation, a series of eco-systematic approaches for controlling Taihu Lake eutrophication were put forward. They are ecosystem regulation, nutrient substances transferring along food chain, trophic masse degrading step by step along the route from a pollution source to the Lake, building ecological preventive zone of the Lake, as well as the ecological measures for point sources treatment and so on.