Abstract: Land use change plays an important role in catchment hydrology cycle and water resources allocation. Understanding the relationship between land use and runoff is an important research content of watershed hydrology. Based on SWAT model, combined with GIS and RS technology and adopting extreme land use analysis method, the runoff response to land use change in Mangniu Basin were analyzed quantitatively using various data derived from watershed DEM, land use, soil and meteorology. It was concluded that in 1998 and 2009, the land use in the basin mainly involved cultivated land, forest land, unused land, the three types of lands accounted for about 90% of the total area; under the same climate condition, monthly and annual runoff presented consistent trend under two different land use scenarios; the annual and monthly runoff in 2009 was slightly smaller than that of 1998, and the average annual runoff reduced by 6.055 million m3; the simulated monthly runoff in July and August decreased significantly; the runoff decreased with the increase of vegetation coverage and otherwise increased; under extreme land use condition, the runoff changes drastically. Therefore, if climate change and other factors are not considered during the study period, the change of land use is the main influential factor to the runoff change.