By using hydrological method,the data of annual rainfall,runoff and sediment from 1956 to 2008 were used to calculate the effects of runoff and sediment reductions by soil and water conservation measures in Uanjiang watershed during the recent 30 years.Results show that the average annual sediment into the Poyang Lake was reduced by 5.7 million tons and sediment reduction was about 48.57%after taking soil and water conservation measures.With the role of the soil and water conservation measures played,sediment reduction rate had increased year by year and then held a stable trend;and sediment reduction rate was 80.54% in 2008.The decrease in annual total runoff was not obvious,while runoff at late stage was increasing.Ecological construction by soil and water conservation could increase the watershed rainfall infiltration,reduce surface runoff,reduce peak flows,extend the convergence time,and play an important role in flood control and disaster mitigation.