In order to scientifically evaluate the runoff and sediment changes and its driving force,the changes of flood process,annual streamflow and sediment load,annual maximum runoff and annual maximum sediment concentration were systemeticly investigation and analysis.The results showed that the occurrence frequency of hyperconcentrated floods was 74% in XiLiuGou basin.Before 1980,the relationship slope between the annual maximum flow and maximum sediment was 1.578 7,but after 2000,the slope values was reduced to 0.331 9,it showed that under the same flow conditions,sediment concentration reduces to one fifth of the last century 80's,through gradual trend test(Mann-Kendall test)and abrupt change test(Pettitt test)method,a significant decline in runoff and sediment load was detected,and the abrupt changes occured in 1997.Water discharge and sediment load of the Xiliugou catchment would be more affected by human activities,while the climate changes in the Basin had little influence.Soil and water conservation measures contribute most to the significant reduction of streamflow and sediment load.