Abstract: This paper studied the evolution process and influence factors of streamflow and sediment into Poyang Lake using linear trend method, double mass curve analysis, empirical statistics method and statistical series comparison method. In the analysis, the measured data of flow and sediment and rainfall from 1961~2016 of several hydrological stations in Poyang Lake were adopted. The results show that the annual rainfall, erosive rainfall and interannual variation of rainfall erosivity all have an insignificant upward trends(P>0.05). The interannual variation of runoff into the lake is not significant, the sediment into the lake has an significant downward trend(P<0.01) with two abrupt change points in 1985 and 2000. The key precipitation indexes that affect runoff and sediment into the lake are annual rainfall and rainfall erosivity. The sediment reduction effects of water conservancy projects calculated by empirical statistics method and statistical series comparison method are 33.4% and 41.8% from 1985 to 1999, 70.6% and 66.8% from 2000 to 2016 compared with 1961~1984 as a referenced period.