Supercritical geothermal resource is a kind of renewable and clean energy with great potential. Its formation and development process is accompanied by strong water-rock chemical reaction. By conducting dissolution experiments of potassium feldspar in pure water at 300~500℃ and 25~50 MPa, this study clarified the influence of temperature and pressure changes on the solubility of potassium feldspar under sub-critical to supercritical geothermal conditions, and revealed the evolution mechanism of its dissolution behavior. The results show that: ① Both temperature and pressure are important factors affecting the solubility of potassium feldspar under subcritical and supercritical geothermal conditions. ② At 400℃, the solubility of potassium feldspar is positively correlated with the pressure. When the pressure is 35 MPa, the solubility of potassium feldspar increases first, then decreases and then increases with the increase of temperature, showing a fluctuation phenomenon. ③ The variation characteristics of the solubility of potassium feldspar are related to the sharp changes in the properties of water (density, hydrogen bond, dielectric constant) under sub-critical and supercritical geothermal conditions. The results contribute to a better understanding of hydrogeochemical processes in supercritical geothermal systems.