Restoration of submersed vegetation is generally considered as an effective long-term approach to improve the water quality of eutrophic lakes,and chitosan-modified soil has been used to rapidly improve the water quality in the recent years.In this study,an experiment with four treatments(the control,submersed macrophyte,submersed marcophyte+soil,and soil) was carried out in the hypereutrophic water(Meiliang Bay) in Lake Taihu during May to December in 2011,with the aim to develop a macrophyte-mediated approach to improve water quality.During the period of the experiment,submersed vegetation had a final coverage of 13.0% and 52.3% in the submersed macrophyte and the submersed macrophyte+soil treatments,respectively.The indices of water quality were measured in 3-day intervals.The results showed that the soil was effective to improve the water quality,with a decrease in the contents of TP by 74.6%,TN by 20.7%,PO₄^3--P by 31.0%,Chl.a by 80.4% and an increased SD by 90.4% as compared to the control;the submersed marcophyte+soil treatment was the most effective way to decrease the contents of TP (64.0%),TN(36.2%),PO₄^3--P(28.6%) and Chl.a(71.1%),and increased the SD(76.4%).The submersed marcophyte restoration alone did not improve the water quality.The submersed marcophyte+soil treatment was also the most effective one among the three treatments to decrease the contents of TN(15.6%),TP(61.7%),PO₄^3--P(55.8%) and NH₄⁺-N(82.8%) in the sediment interstitial water.The study implies that restoration of submersed vegetation with the aid of chitosan-modified soil be an effective technology to improve the water quality,although the effectiveness needs to be further evaluated on a long-term basis.