Taking Panjiakou Reservoir watershed as study area ,the paper applied distributed mechanism hydrological model SWAT(soil and water assessment tool) to quantitatively evaluate the effects of land use change on runoff process in the watershed.The changes land use in 2006 mainly showed the reduction of agricultural land the increase of forest and pasture area compared with that in 1980 ,and there were little changes in water area and urban land. It used observed monthly flow data from Jan.1986 to Dec1999 at three hydrologic stations to calibrate and validate the model.It simulated the natural runoff processes in different land use scenarios. The results showed that compared with land use scenarios of 1980,the average runoff of many years in 1986 decreased by eleven percent.For different typical hydrological years, the influence of land use change on runoff is the greatest in dry years and is general in wet years and mean years; the influence of land use change on runoff mainly indicated the decrease of runoff in flood season.The result shows that water conservation capacity of Panjiakou Reservoir watershed is increasing in resent years.The study on impacts of land use change on runoff in Panjiakou reservoir watershed has practical significance for the plan of reasonable land use and comprehensive management of local water resources.