Abstract: Based on hydrologic analysis this paper quantitatively researched the contribution of precipitation and human activities on streamflow and sediment load. The present study applied simple linear regression, Mann-Kendall test, accumulative annual anomaly and flow duration curve method to investigate the variation of streamflow and sediment load in the Huangfuchuan Watershed in the middle reaches of the Yellow River according to the measurement data from 1955 to 2010. Significant reduction in both streamflow and sediment load were detected, as well as abrupt changing point in 1979 was found. Average annual streamflow and sediment load during 2000 and 2010 are extremely low, accounting for only 20% of those from 1950 to 1959. Human activities accounted for approximately 70% of reduction in streamflow and sediment load, and the remains was attributed to decreased precipitation. Since the early 1980s, a series of large-scale soil and water conservation measures (e.g. returning cropland to forests, grassland, terracing, reservoirs and check-dams construction) are the dominant factors leading to significant reduction in streamflow and sediment load in the Huangfuchuan Watershed.