In this study, the sources of potentially toxic elements (PTEs) from atmospheric deposition in the waters of Guizhou's Caohai Lake were investigated in addition to the potential risks to human health. Moss bags were used to enrich PTEs from atmospheric deposition, and eight monitoring sites that best represented geographic variation were established around Caohai Lake. Moss bags were collected and examined at every 3 months to identify spatiotemporal patterns of dry and wet atmospheric deposition of PTEs. Zn was the most abundant metal identified from deposition in Caohai (72.07%-95.94%), followed by Pb and Cd, while Hg was the least abundant (0.008%-0.354%). The contributions of wet deposition of PTEs were greater than those of dry deposition, and deposition during the heating season from December to April was greater than that between April to July. Hg was mainly derived from atmospheric dry deposition (65.38%-84.44%). Spatial distribution analysis indicated that atmospheric deposition was associated with the intensity of human activities and heating emissions. Exposure via hand-to-mouth contact accounted for over 99% of the total exposure risk although overall exposure was lower than threshold acceptable levels for carcinogenic and non-carcinogenic metals, indicating an overall lack of risk towards human health. Nevertheless, the health risk from atmospheric deposition of PTEs in Caohai Lake may be reduced by focusing on Zn, Pb, and Cd deposition in rainfall and minimizing the hazards associated with hand-to-mouth exposure to PTEs.