Heavy metal pollution in soils has become increasingly prominent. To explore the distributions of heavy metals in soils in Fangshan District, Beijing, China, this study collected 152 topsoil samples and 240 deep soil samples from this district. Based on these samples, this study statistically analyzed the distributions and enrichment factors (EF) of seven heavy metal elements, namely As, Cd, Cr, Cu, Hg, Ni, and Pb. Furthermore, this study investigated the correlations, sources, and contribution rates of these elements through principal component analysis (PCA) and positive matrix factorization (PMF). The results show that: ① Elements As, Cd, Cu, Ni, and Pb exhibit high contents in the topsoil of the Shidu, Shijiaying, Xiayunling, and Puwa areas. Besides, elements Cr, Ni, and As manifest high contents locally in Zhoukoudian, Nanjiao, and Hebei Town. Element Hg displays high content in the eastern plain areas including Doudian, Yancun, and Changyang; ② Elements Hg and Cd are highly enriched, and there exist strong corrections among elements As, Cr, and Ni; ③ These elements primarily originate from natural sources (soil parent materials), which contribute to 73.6% to 78.6% of the elements. Element Cd is mostly sourced from an anthropogenic mixed source, which contributes 83.3% of Cd. The mixed source predominantly consists of industrial and mining activities, agricultural production, and traffic emissions. Elements Cu and Pb showed similar contribution rates of natural and mixed sources, both about 50%. Element Hg in soils primarily stems from dry and wet atmospheric deposition, which yields a contribution rate of 72.4%.