Since the spatial and temporal distribution of water resources in China has changed under the impact of climate change, the government urgently needs the adaptation strategy to the change. The hydrological cycle is the theoretical basis of the water resources problem. Additionally, hydrological cycle in the arid-humid transition zone is very sensitive to the climate change. Therefore, this research aims to investigate the response mechanism of hydrological processes to climate change in the arid-humid transition zone of China. The research would be helpful for the water resources management of China under climate change. The main research includes: 1) investigate the swing range of the arid-humid transition zone during last decades; build the sensitive index which comprehensively indicates the sensitivity of hydrological cycle to climate change; 2) analyze the inconsistency of evapotranspiration estimation from water balance model and energy balance model, and develop a distributed water cycle integrated simulation system based on the coupled water and heat process; 3) reveal the mechanism of nonlinear response of evapotranspiration and runoff to climate change based on the hydrological modeling, indoor tests and field investigation. 4) estimate the future trend of runoff in the arid-humid transition zone of China based on the comprehensive analysis of the impacts of climate change and human activities.