Most of the heavy metal-related deposits are distributed in watersheds of mountainous areas, and the enrichment of soil heavy metals were affected by both natural high background and anthropogenic source in the area. It is particularly important to formulate precaution countermeasures to accurately identify and quantify the source of soil heavy metal pollution in the ore-concentrating area. This paper studies the surface soil of a small basin in Beishan Reservoir which was rich in ores. Based on the evaluation of the heavy metal accumulation degree, the pollution sources identification and their contributions to soil heavy metals were studied by multiple methods including field investigation, multivariate statistical analysis, positive matrix factorization(PMF), spatial analysis, and other methods. Conclusively, the accumulated Cu and Cd in the top soil were higher than other heavy metals, the Cu and Cd average contents were 3.05, 3.47 times as high as the regional background value, and exceeded the soil risk screening values. About 10% of samples reached the level of moderate to severe enrichment. The heavy metal pollution sources in the topsoil were jointly affected by natural geological background, mining activities, and agricultural activities source. The contribution rates of mining activities to Cu and Cd are 68.92% and 56.31%, and natural geological backgrounds also contribute 21.05% and 38.35% to them. The natural source contributed most to As, Cr, and Ni, with contribution rates of 83.13%, 72.59%, and 78.76%, respectively. Hg mainly comes from agricultural activities, and its contribution rate was 81.79%. Zn and Pb were affected by both material migration and natural geological background. The reliability and rationality of the analytical results for the heavy metal pollution sources can be improved by the mutual verification of the combination using different methods. [ABSTRACT FROM AUTHOR]