Abstract: The distribution of high-fluoride groundwaters in the import region of the Dongshan water transfer project was investigated.Regional hydrogeochemical survey indicates that the high-fluoride groundwaters are characterized with slightly alkaline pH values as well as high concentrations of HCO^-₃ and Na⁺,thus their hydrochemical types being predominantly HCO₃-Na.The major processes responsible for the formation of high-fluoride groundwaters in the study area include dissolution of fluoride-bearing minerals and ion exchange between OH^- in groundwater and F^- in mica minerals.In addition,the evaporation in the discharge area and the discharge of industrial wastewaters containing fluoride may also have non-negligible effects on the occurrence of high-fluoride groundwaters.