Assessment of climate change and land use/cover changes (LUCC) on hydrological processes is essential for the sustainable development of water resources,especially in the arid/semi-arid regions with limited water supplies.The Soil and Water Assessment Tool (SWAT) was used as a distributed hydrological model to quantify the effects of climate change and LUCC on seasonal variation of surface runoff and evapotranspiration in the Gulang River basin.The results suggested that the variation of precipitation and temperature is the major reason for the variation of evapotranspiration and surface runoff.Surface runoff is more sensitive to precipitation than temperature whereas temperature has a greater impact on evapotranspiration with an obvious seasonal variation.Moreover,LUCC can result in the variation of evapotranspiration and surface runoff as well.The increasing of forest or grass land can increase evapotranspiration but decrease surface runoff,the increasing of agricultural land can decrease evapotranspiration and surface runoff,and the increasing of rural residential area or bare land can increase both evapotranspiration and surface runoff significantly.