Abstract: The trend of ecological succession was studied for the past 50 years in Taihu Lake.With the passage of time ,the water quality has been worsening and sediment thickening ,while the density of phytoplankton has been increasing,species richness decreasing with the smaller species becoming dominant.The trophic status shows the tendency from meso-eutrophic type to near eutrophication.Potamogeton malialaianus was the dominant species of submerged plants in 1950s,but the rate of swamp forming is more rapidly due to the increasing sedimentation and rapid growing of emerging plant and leaf-floating plant after 1990s.Density and biomass of benthos raised from 1959 to 1989, but natural resources and biomass of mollusca reduced after 1990s rapidly because of pen fish culture and excessive catching,total yield of fisheries continued to raise.Since 1984,pen fish culture converted from extensive models to intensive ones,the culture species were shifted from regular species to high valued species, from heavy pollution and enviroment-hostile to ecological types.The comprehensive control and ecosystem rebuilding in Taihu Lake must be emphasized and carried out so as to maintain the sustainable development of lake resource.