In order to explore the response of runoff to land use and climate change in Minjiang & Tuojiang River Basin，a hydrological SWAT(soil and water assessment tool) model of Minjiang & Tuojiang River Basin was constructed to quantitatively evaluate the effects of land use and climate change on the runoff in Minjiang & Tuojiang River Basin from 1981 to 2014 on spatio-temporal scale using scenario analysis. The results show that the SWAT model is applicable to the runoff simulation of Minjiang & Tuojiang River Basin. Both climate and land use change will induce a decrease in runoff in this basin, and the influence intensity of climate change is significantly greater than that of land use change. They have the greatest influence on the runoff of Dadu River and Tuojiang River respectively. Only considering climate change, the runoff is positively correlated with the percipitation change, but negatively correlated with the temperature change in this basin. In addition, climate change has the greatest impact on the runoff of Dadu River. When only considering the land use change, both the conversion of cultivated land of 25 °slope and above into forest land and cultivated land of 15 °-25 ° slope into grassland will cause a slight reduction of runoff in this basin, and the former has the greatest impact on the runoff of Dadu River, the latter on Minjiang River, respectively. The conversion of all forest land into grassland will lead to a slight increase in the runoff with the largest increase in Dadu River.