Abstract: Researches and study of geothermal water occurring in the Yuehe basin, thermal water chemistry and 2H,18O, and 3H, and 14C isotopes from the geothermal water wells in Hengkou area, original source, changes and evolution of geothermal water in Hengkou and isotopic hydrological characteristics indicated that the chemical type of geothermal water in Hengkou geothermal well is sodium bicarbonate type（HCO3-Na）. The cations in geothermal water are mainly Na+ and K+, and the anions are mainly HCO3-and CO32-, mixing with a part of modern atmospheric precipitation and forming a mixture of ancient water and modern water. According to the radionuclide of 3H and 14C, the age of geothermal water is determined to be 32520 ±1780a. According to the hydrogen and oxygen stable isotope, the main recharge elevation of geothermal water is calculated to be 1,423m upward, it is inferred that the main supply areas are Fonghuangshan Mountain at the south of the Yuehe Basin and Niushan middle-high mountain area in the north.