Abstract: This study is to provide an identifiable ground for development and utilization of water resources in the Kuye River basin under the direct impact of abnormal climate changes and human activities. According to trend analysis on the annual runoff series at the Wenjiachuan hydrologic station in the basin from 1954 through 2010, MK-P method and Pettitt test were used to detect the abrupt points in this series, and the contribution ratios of rainfall, potential evaporation, and human activities on the runoff were calculated by the method of slope change ratio of cumulative quantity (SCRCQ). Results show that the series has significant decreasing trends and mutation features with two abrupt points that occurred in 1979 and 1996. Relative to the reference period 1954—1979, the impact proportions of annual precipitation, annual potential evaporation, and human activities on runoff were 29.2%, -3.6%, and 74.4% respectively in the period 1980—1996 of low human activity intensity, and 20.6%, -1.5%, and 80.9% in 1997—2010 of high intensity. If compared with the period of low human activity intensity, the impact proportions were 11.9%, -0.2%, and 88.0%. Large-scale water and soil conservation measures and high-intensity coal mining have produced significant effects on the mutations in the Kuye River runoff.