Geothermal water occurring in Fengliang area of Guangdong province has temperature as high as 96℃ and it is found in the fractured prophyrite of the lower Jurassic period. Fluorine concentration is high in geothermal water and has caused food poisoning before. This paper is intended to study the recharge sources, circulation and evolution of the geothermal fluid with high fluorine content and possible reservoir temperature for future sustainable development.Methods: Geothermal water and local surface water were collected for water and gas chemical and isotopic analysis. In addition, geochemical simulations to compute the fluorine species and saturation index of certain minerals were also applied. For reservoir temperature calculation, geothermometers with mixing and degassing correction were used based on geochemical processes occurring from deep to surface.Results:There are two types of geothermal water. A type geothermal water is of HCO-3—Ca2+ type with high concentration of Ca and low concentration of Na and K and temperature is below 40℃. B type geothermal water is of HCO-3—Na+ type with high concentration of Na and K and low concentration of Ca and temperature is higher than 40℃. The fluorine content is about 15.0~22.6 mg/L. Geothermal gas is dominated by N2 and also contains seldom CO2, Ar and O2, indicating the sources of air and crust.Conclusions: A type geothermal water may be affected by mixing of shallow groundwater but evidences were missing. B type geothermal water is the deep geothermal fluid. It is recharged by the local mountains and infiltrates through fractures to porphyrite reservoir and the circulation depth and water—rock interactions time can achieve 5200~6300 m and 22 ka. Dissolution of the alumino- silicate minerals and cation exchange promote the formation of geothermal fluid with high concentration of N2, SiO2, F, Na, Sr and Li. During the ascending processes, mixing by Hanjiang River water (mixing ratio is about 10%~25%) and slightly CO2 degassing (steam fraction is about 0.3%~0.5%) occurs. F concentration is constrained by dissolution of fluorite and it is positive correlated with temperature and pH. Based on the mixing and CO2 degassing correction, the deep reservoir temperature is about 138~143℃ and this is consistent with TangKeng geothermal system in the south, indicating that they may belong to the same geothermal system.