In the context of global warming, the impact of human activities on river runoff continues to strengthen,which results in happening the problems of runoff reduction,dried up and variation of runoff and sediment in northwest arid and semi-arid regions.Therefore，it's very important to explore the variation characteristics,trend and internal cause of runoff and sediment load in Jialu River. The paper used the methods of moving average and sequential cluster to analyzed the variation characteristics of runoff and sediment load from 1957 to 2010,and applied hydrologic analysis to quantitatively analyze the effect of precipitation and human activities on runoff and sediment load. The result showed that both runoff and sediment load presented the decrease trend, and took place the change point in 1972.The average runoff after 1972 accounts for only that of 21.56% before 1972, the annual sediment load obviously reduces and accounts for 6.45% of that before.The impact of Human activities on the reduction of runoff accounts for 81% and that of sediment load accounts for 67.23%.The impact is different in different periods but possesses the gradual strengthening trend contribution on the whole. Human activities are the dominant factors leading to reduction of runoff and sediment load and the decreasing trend will continue in the current climate conditions in Jialu River watershed.