Objectives: In order to support the development and sustainable utilization of the Reshuitang hot spring tourism in Gugan Shui nationality township, Eastern Yunnan. 〖WTHZ〗Methods: The formation mechanism and physiotherapeutic value of the Reshuitang hot spring were studied by collecting water samples for hydrochemistry and environmental isotope analysis.  〖WTHZ〗Results: The temperature of the Reshuitang hot spring is 37.8~42.2℃, the pH value is 7.24~7.75, and the TDS is 1245~1840 mg/L. It belongs to medium—low temperature ,weak alkaline, hot mineral water. The content of H2SiO3 in the hot spring water is 48.20~60.57 mg/L, the content of F is 2.86mg/L~2.94 mg/L, and the content of Sr is 8.60~14.40 mg/L, which all meet the water quality standards of physical therapy hot mineral water of silicon water, fluorine water and strontium water. In addition, the concentration of 222Rn in the hot spring water reaches 129.4 Bq/L, which is close to the physical therapy water quality standard of radon water. So the Reshuitang hot spring has great development and utilization value. The cations in the hot spring are mainly Ca2+ and Mg2+ , and the anions are mainly SO2-4and HCO-3. The hydrochemical type of the Reshuitang hot spring is SO2-4—Ca2+·Mg2+ type. The dissolution of gypsum and carbonate minerals is the main factor controlling the hydrochemical characteristics of the Reshuitang hot spring, in which the dissolution of gypsum plays a dominant role. Conclusions:δ13C value of CO2 participating in water—rock reaction is -11.64‰~-14.24‰, CO2 involved in water—rock reaction in hot spring water comes from sedimentary organic matter. 14C dating results show that the age of the Reshuitang hot spring is 3291 a BP. The hydrogen and oxygen isotope characteristics show that the Reshuitang hot spring is recharged by atmospheric precipitation.The recharge elevation is 2101.9m~2138.3m,and the temperature in the recharge area is 5.9℃~6.2℃. The silicon enthalpy equation method is used to calculate that the cold water mixing ratio of the Reshuitang hot spring is 0.84~0.89. Based on the heat storage temperature calculated by the silicon enthalpy equation and the heat storage temperature calculated by the corrected SiO2 geothermal temperature scale, it is considered that the heat storage temperature of the Reshuitang hot spring is 173.1℃~220.3℃, and the circulation depth is 2059.7m~2661.1m.