Northwestern Sichuan and southern Gansu (NSSG) is located in the source areas of Yellow River and Yangtze River. Quantitative study of soil erosion in this area is of great significance for ecological security of large river source region and sustainable development of local economy. In this study, variously sourced data, combined with a variety of methods were used to quantitatively evaluate the temporal and spatial distribution characteristics and change rules of soil erosion in NSSG from 2000 to 2015 based on USLE. The results showed that:(1) R values representing rainfall erosivity ranged from 65 to 411 (MJ·mm)/(hm²·h·a), and the high values were mainly found in southeast part, and the spatial distribution of high values was consistent with the rainfall pattern. (2) Soil erodibility K ranged from 0.19 to 0.41 (t·hm²·h)/(hm²·MJ·mm), the high values sporadically distributed in space, which was mainly influenced by the physical and chemical properties of zonal soil. (3) The slope length and slope gradient factor LS ranged from 0 to 8.24, the high values were mainly distributed in high mountains of the middle and North parts of research area, while the low values were found more in the northeast and southwest regions with gentle terrain. (4) Factor C of vegetation cover management ranged from 0 to 1, the high values were concentrated in the northwest and southwest parts, where the vegetation cover was relatively low. (5) Based on USLE, the annual erosion amount of NSSG was 3.3×10⁸ t/a, which was generally characterized by mild erosion. (6) From 2000 to 2015, soil erosion in NSSG showed a weakening trend, which was related to the enhancement of vegetation activities under the background of warming.