北京大兴地区西南部第四系地下水氟含量普遍超标，严重制约区域供水。通过取样化验，分析了研究区高氟地下水的分布特征和分布范围。综合区域水文地质、地貌、地质构造、地层岩性及水化学等方面特征，分析了高氟水的成因，认为浅层高氟水的形成机理属于F-蒸发浓缩富集型，而深层高氟水中的氟则是来自于基底富氟白云岩。研究成果对区域供水井的设计施工，以及保障区域供水安全具有现实社会意义。

Fluoride content in groundwater generally exceeds the standard in the southwest of Daxing district in Beijing, which seriously restricts the regional water supply. In this paper, the spatiotemporal distribution characteristics and range of high-fluoride groundwater were analyzed based on the sampling and chemical analysis of groundwater in the study area. The genesis of high-fluoride groundwater was analyzed according to regional hydrogeological , topographical, geological structures, hydrogeological, lithological, and water chemical characteristics, which suggested that shallow high-fluoride groundwater was due to evaporation preconcentration, and the fluoride content in deep groundwater was from fluoride-rich dolomite of basement rocks. This output is of great significance to the design and construction of regional water supply wells and the safety control of regional water supply.