Abstract: Taking the Panlong River Basin as the study area and using the SWAT model,by setting different extreme land use scenarios,this paper analyzes quantitatively the order of contribution of main land use types in the basin to runoff,and the specific impact of vegetation cover changes on the runoff process in the basin,and further discusses the influence of basin water replenishment project and runoff in high and dry seasons on the runoff of the Panlong River. The results show that:（1）The contribution of the three land use types of woodland,grassland and cultivated land to the river runoff production in the basin is:cultivated land is the strongest,followed by grassland,but it is roughly equivalent to the impact of cultivated land on runoff formation,while forest land is the weakest；（2） From 2007 to 2014,the vegetation cover structure in the Panlong River Basin changed significantly. Among them,the area of forest land decreased by 7.31%,while grassland and urban construction land increased by 5.05% and 2.82% respectively. Most of the reduced forest land was converted into grassland and urban construction land.Although the ebb and flow of forests,grasslands,and urban land enhances the runoff effect,it aggravates the annual variation of runoff and weakens the functions of vegetation in the watershed to conserve water and regulate runoff.（3） After the water replenishment project was put into operation,the annual runoff of the Panlong River showed a large increase in 2014,which was completely opposite to the annual decrease trend from 2007 to 2013,and the runoff increase in the dry season was significantly higher than that in the wet season,and the runoff regulation effect was obvious.（4） The change of the runoff in the dry season is the main reason for the change of the annual runoff trend of the Panlong River from 2007 to 2014.