In recent years, numerous rivers around the world have shown significant changes in runoff due to climate change and human activities. Investigating the causes of changes in runoff is greatly helpful in adapting to climate change and intensive human activities. The present study applied the Mann-Kendall test and the double mass curve method to assess the temporal trends of hydro-climatic variables in the Wei River basin during 1958-2015. The results showed that annual runoff at all three hydrological stations (Xianyang, Zhangjiashan, and Zhuangtou) exhibited a significant decreasing trend (P < 0.05). Annual rainfall and potential evapotranspiration showed decreasing and increasing trends, respectively, but neither were significant. Double mass curve analysis between annual runoff and precipitation showed abrupt changes in annual runoff in the Wei River basin. The periods before abrupt-change points, when runoff retained relatively pristine status and was affected by limited human activities, were regarded as baseline periods. Using the abrupt-change points, we obtained baseline periods of 1958-1970, 1958-1996, and 1958-1992 at Xianyang, Zhangjiashan, and Zhuangtou stations, respectively. The runoff elastic coefficients at each station were estimated using the Budyko hydrothermal equilibrium equation. The results showed that runoff depth was sensitive to the changes in land surface. Compared with runoff in the mainstream Wei River and the Jing River, runoff in the Beiluo River was less sensitive to climate changes. Land surface changes played a dominant role in runoff reduction, followed by precipitation and potential evapotranspiration. Particularly in the mainstream Wei River and Jing River, land surface changes resulting from various human activities contributed more than 60% of runoff reduction.