Based on source-sink landscape theory, the relationship between spatial pattern changes and soil erosion from 1995 to 2010 was studied using method of Location-Weighted Landscape Index (LWLI) in Guanchuanhe River basin, Dingxi, Gansu Province. Following results were captured. First, it showed that the values of LWLI_elevation,LWLI_distance and LWLI_slope decreased gradually from 1995 to 2010. In the areas with high altitude or with long distance from basin outlet, source landscape contributed less than sink landscape. Forestland was mainly distributed in low gradient region, while grassland was mainly distributed in the areas with steep slope. Second, LWLI declined continuously from 1995 to 2005, and there was a slight increase from 2005 to 2010, which indicated that the pressure of farmland expansion was still high because of population expansion and natural resource limitation. Third, in the past two decades, no significant change was detected for precipitation in this region, while river runoff, runoff coefficient and soil erosion modulus all decreased in Guanchuanhe River basin. Soil erosion modulus has a positive correlation with LWLI (P<0.05). Therefore, it was considered that LWLI can correctly reflect the effect of source and sink landscape on soil erosion, and LWLI can be used as a valid tool to evaluate the potential risk of soil erosion. Our study would provide scientific basis for better understanding the relationships between "Grain for Green" project and its hydrological effects in the basin, helping to control severe soil-water loss and achieving wise ecosystem management on the Loess Plateau.