Abstract: Abstract: Located in northwest Zhunhua City of Hebei Province, Tangquan has piedmont hilly landform with abundant geothermal resources. The authors analyzed the geothermal fluid of this area. According to the results obtained, Na⁺, Ca²⁺, K⁺, Mg²⁺, SO^2-₄, HCO^-₃, Cl^- and NO^-₃ are major elements of the geothermal fluid of this area; hydrochemical types are mainly SO^2-₄-Na⁺; the geothermal fluid is unpolluted and natural weakly alkaline water; the average content of F^- of the geothermal fluid is 9.36 mg/l, which is much higher than the national standard of V grade groundwater quality; the content of soluble SiO₂ of the geothermal fluid in this area can be used as a geothermometer; the total salinity of the geothermal fluid is 782.33 mg/l on average, being of fresh water; the geothermal fluid belongs to medium corrosive water, which does not form CaCO₃, CaSO₄ -2H₂O or SiO₂ scales; the geothermal fluid belongs to continental sedimentary water formed in the strata with dissolved salt brine. The hydrogen and oxygen stable isotopes show that the geothermal fluid of this area is mainly derived from meteoric water.