Abstract: Investigating soil erosion in the Three-Rivers Headwaters area is of great significance for the protection of the ecology, production, and function of the alpine meadow ecosystem on the Qinghai-Tibetan Plateau. In this study, we conducted a comprehensive analysis of soil erosion, its spatial characteristics, and the factors affecting it in the Three-Rivers Headwaters area. For these analyses, we used a ¹³⁷Cs tracing technique, GIS (Geographic Information System), and the RUSLE (Revised Universal Soil Loss Equation) model. The results showed that: 1) soil erosion factors showed spatial heterogeneity. Rainfall-related erosion showed drastic inter-annual changes, but generally increased from 2001 to 2012. Soil erodibility varied spatially, and soils with a high erodibility index accounted for 95.66% of the total area. The spatial distribution of slope and slope length were significantly influenced by the altitude. The vegetation cover and management factors showed spatial heterogeneity from the northwest to the southeast of the study area, and overgrazing was the main cause of serious underlying surface erosion. 2) In the validated RUSLE model, the correlation coefficient was 0.49 and the average root mean square error (ARMSE) was 75.29%. Although the RUSLE model tended to overestimate soil erosion, it was still one of the best choices to simulate alpine meadow soil erosion in the Three-Rivers Headwaters area. 3) The total average erosion volume estimated by the RUSLE model (2001-2012) was 3.1×10⁹ t/yr. Analyses of the erosion intensity classifications revealed the areas of moderate, strong, and extremely strong erosion. The three areas with the highest degrees of erosion were Tanggula township, and Zhiduo and Xinghai counties. 4) Taking into account the amounts of soil loss and market values, the estimated average economic loss of organic matter was 114354 RMB/km² in the study area from 2001 to 2012, the total annual economic loss was 39.9 billion, and economic losses caused by soil erosion were substantial across the whole study area. Therefore, it is very important to develop “classification, grade, segment, partition” soil erosion prevention and control procedures for the Three-Rivers Headwaters area of the alpine grassland on the Qinghai-Tibetan Plateau.