The Tangchi geothermal field in Kunming is situated in the anticlinal core at the junction of the Yangtze Paraplatform and the Western Yunnan Fold Belt. Characterized by well-developed water-rich carbonate rocks and water-conducting faults, the region possesses abundant geothermal resources. However, a systematic understanding of its deep groundwater circulation pathways, water-rock interaction processes, genetic mechanisms, and resource potential remains lacking, which hinders the sustainable development and utilization of its geothermal resources. To this end, this paper comprehensively employs geological structural analysis, stable isotope tracing, hydrochemical plotting, and geothermometry to systematically analyze the hydrochemical characteristics and genetic mechanisms of the Tangchi geothermal field. We identify its recharge sources and circulation depth, ultimately establishing a genetic model of the geothermal field and estimating its geothermal resource capacity. The results show that the hydrochemical types in the Tangchi area are complex and diverse, includingHCO3·SO4-Na·Ca,SO4·HCO3-Na·Ca·Mg,HCO3·SO4-Ca·Mg·Na,SO4·HCO3-Na·Ca,and HCO3·SO4-Ca·Na·Mg.The hydrochemical characteristics are primarily governed by the dual dissolution of carbonate and silicate minerals, superposed by cation exchange and the mixing of shallow cold groundwater. Atmospheric precipitation serves as the primary recharge source, with recharge elevations ranging from 2 364 m to 2 522 m. Meteroic water migrates downward along anticlinal fractures, absorbing heat from surrounding rocks within the geothermal reservoir and dissolving host rocks. During this circulation, cation exchange and the saturation precipitation of carbonate minerals occur. The circulation depth of the groundwater ranges from 3 205 m to 4 382 m, with estimated reservoir temperatures between 109 °C and 143 °C and cold-water mixing ratios of 46 % to 89 %. The total static thermal energy storage is estimated at 5.41x1012 ,orresponding to a geothermal energy capacity of 2.26×1013 kJ, which is equivalent to approximately 7.73×105 t of standard coal. This study reveals the water-rock control mechanisms of rock dissolution and cation exchange adsorption in the Tangchi geothermal system. By applying a silicon-enthalpy mixing model, it quantitatively decouples the proportion of cold water influx, eliminating biases from conventional geothermometers and enabling more accurate calculation of reservoir temperatures. Integrating regional geological structures, a geothermal genesis model for the study area is established, along with an assessment of resource potential. The research achieves a transition from qualitative description of water chemistry to quantitative characterization of deep thermal dynamics, providing crucial theoretical support for the scientific development and conservation of geothermal resources in the Tangchi field.