Land use and climate are two main factors directly influencing catchment hydrology and water resources.The separation of their effects is of great importance for land use planning and water resources management.On the basis of statistical analysis of the change trend of meteorological factors and land use from 1980 to 2014,we assessed the impacts of climate change and land use change on the runoff change in the upper reaches of Wenyu river by combining SWAT model simulation and scenarios designing.Results indicated that the SWAT model is a powerful tool to simulate the effect of environmental change on runoff in the upper reaches of Wenyu River.The correlation coefficient R2 and Nash coefficient Ens were 0.80 and 0.79 respectively during the calibration period,and were 0.77 and 0.74 respectively during the validation period.The rainfall and temperature gradually increased;the forest land and cultivated land decreased gradually;the urban and rural areas increased gradually; and the grassland gradually increased during 1995 to 2005.These changes synthetically affected the runoff and caused the runoff to increase first and then decrease.The contribution rate of climate change to runoff was 100.46%,and the contribution rate of land use change to runoff was 2.09%.The climate change had greater influence on the runoff than the land use change in the upper reaches of Wenyu River during 1980-2014.Therefore,how to cope with climate change is worthy of attention in the water resources management.