The numerical model HydroTrend is applied to simulate the variations of water discharge and sediment fluxes into Poyang Lake during 1956- 2010 from the five tributaries of Poyang Lake Basin, namely Gan, Fu,Xin, Rao and Xiu rivers. Furthermore, the influences of climate change, vegetation cover variation and reservoirs construction on the sediment load are analyzed, and the contribution of the above three factors to the sediment load entering the Poyang Lake is quantitatively evaluated. The results show that, during the period of 1956-2010, the average annual sediment discharge into Poyang Lake under the influence of climate, vegetation cover and reservoir construction reached 15.5 Mt, 20.8 Mt, 8.5 Mt, respectively; whereas, the sediment load entering the Poyang Lake under the combined- influence of the above three factors is 12.6 Mt a~(-1). In addition, during the same period, the sediment load delivered to the Poyang Lake increased by 4.2 Mt a~(-1) due to water and soil erosion, and decreased by 8.2 Mt a~(-1) attributed to reservoir interception, which accounted for 32.4% and 63.2% of the observed sediment load discharged into the Poyang Lake, respectively. From 1956 to 1989,the increased sediment load caused by water and soil erosion and the decreased sediment load induced by dam emplacement, in terms of both quantity of 5.1 Mt a~(-1), is equivalent; However, during 1990-2010, the sediment load resulting from water and soil loss decreased to 2.7 Mt a~(-1), and that intercepted by reservoirs increased to 13.3 Mt a~(-1), suggesting that the effect of reservoirs construction on the changes of sediment load entering the Poyang Lake is 5 times of that of water and soil erosion.