Located in the Longzhong Loess Plateau of northwestern China,the Zulihe Basin was selected as the study area.It sits in a transition zone with a 200 to 400 mm annual precipitation,one of the most sensitive and complex regions to the climate change.The local climate is characterized by hot summers and cold winters with relatively concentrated rainfall during the wet season (from June to September) which often leads to severe soil erosion.The information about the precipitation,runoff and sediment discharge in the basin were collected from 1955 to 2013 and were examined first using the Mann-Kendall (M-K) method to reveal their changing trends.Then,the influencing factors on runoff and sediment discharge,especially various soil and water conservation practices on soil erosion were studied based on regression analysis..The results suggested an overall downward trends in runoff and sediment discharge in the basin with some similarity to the trend in precipitation.However,the magnitude of downward trend of sediment discharge and runoff differed in different periods.It varied a lot for the precipitation in wet and dry seasons,with an annual precipitation of 376.2mm in wet season during the time period from 1955 to 1989 and an annual precipitation of 224.9mm in dry season from 1999 to 2013.The year 1995 was the breaking point for the precipitation and runoff during the study period after which the precipitation and runoff were significantly decreased.For the sediment discharge the breaking point during the study period appeared in 2000.According to UF_k values about runoff and sediment discharge,the whole time span of this study was divided into four periods which included a nonremarkable reduction period (from 1955 to 1971),a remarkable reduction period (from 1972 to 1985),a significant reduction period (from 1986 to 2000),and an extremely significant reduction period (from 2001 to 2013).It was found the various soil and water conservation practices such as terraces construction,afforestation,grass land establishment,natural wildland preservation,and establishment of runoff holding ponds played an important role resulted in the downward trend in soil erosion.The findings from this study will not only explain the long-term variability in soil erosion but also provide insight for guiding future soil and water conservation programs in this basin and even in other regions of similar conditions.