Abstract: As the water source of the Middle Route of South-to-North Water Diversion Project, the water quality safety of Danjiangkou Reservoir directly influences the water supply security and ecological health of the receiving areas. To systematically assess the heavy metal pollution status of the reservoir, we analyzed the temporal and spatial distribution characteristics and change trends of heavy metal concentrations in the reservoir waters based on monitoring data from 2014 to 2023. The results indicated that concentrations of heavy metals in the reservoir area were at a relatively low level, except for antimony in the Baidutan section in 2014, which exceeded the GB 3838—2002 standard limit. Among the 19 heavy metals monitored, concentrations of molybdenum and antimony were significantly higher than the background values of the Hanjiang River system. From 2014 to 2023, the concentrations of six metals, including antimony, molybdenum, arsenic, vanadium, barium, and iron, showed an overall trend of first decreasing and then stabilizing. Affected by the autumn flood season, the concentration of antimony in the reservoir water in 2023 had slightly increased compared to 2022. Concentrations of these six heavy metals at the Baidutan section of Dan part of the reservoir were highest among all sections, and the long-term mean concentrations of barium, arsenic, molybdenum, antimony, and vanadium in Dan part were also higher than that in the Han part of the reservoir, which was related to factors such as the rich mineral resources of antimony, molybdenum, and high background value of heavy metals in Danjiang River and its branch Laoguan River basin at upstream of Dan part. The research findings can provide a scientific basis for heavy metal pollution prevention and control in the water source area.