According to the water analysis result of geothermal well in Huaxian, the paper carried on the water-rock interactions analysis and determined balanced mineral and the balance temperature scope in the geothermal water based on the equilibrium distribution calculation of water miscible component. The thermal resevoir temperature was estimated using geochemical thermometer scale such as SiO2. Otherwise, according to principle of this geochemical thermometer scale and the reality of geothermal water in Huaxian, the paper discussed the formation environment of geothermal water, applicability of geochemical geothermometer scale and reliability of the estimate result.