Wuli Lake of Taihu Lake region is a typical hyper-eutrophic,shallow lake in China,situated near the Wuxi City in Jiangsu Province.Since January 2004,a large-scale macrophyte restoration experiment(105 m²) was carried out in southwestern Wuli Lake using a large enclosure.The results show that from August 2004 to July 2005 mean concentrations of PO3-4—P and NH+4—N of submerged area and macrophyte area inside the enclosure were 54.6% and 46.7%,17.1% and 13.8%,lower than those of outside enclosure,respectively,implying markedly improved water quality inside the enclosure.Phosphate releasing simulation from the cores collected from different areas in enclosure and outside enclosure was conducted in the laboratory.The resulted showed that the mean phosphorus release rates of the sediment from the submerged area and macrophyte area inside the enclosure were 0.23±0.42 mg/(m²·d) and-0.38±0.65 mg/(m²·d),respectively,contrasting to 1.13±1.31 mg/(m²·d) outside the enclosure.Overall,rehabilitated macrophyte not only decreased the concentrations of nitrogen and phosphorus,but also controlled the phosphorus release rate of sediments.