<p>Accurate thermal properties of geothermal reservoir rocks are significant for evaluating the performance of geothermal systems; however, the potential influence of the reservoir in-situ high-temperature and high-stress conditions is still not fully considered. This study reported the thermal conductivity, the specific heat capacity, and the thermal expansion coefficient of Gonghe granite, Kangding granite, and Songliao sandstone under varying temperatures or axial stresses. A numerical model was developed to simulate the heat extraction process by incorporating thermal-hydro-coupling effects based on experimental data. It indicated high temperatures lower the thermal conductivity, whereas the thermal conductivity increases with the stress. The heat storage capacity and thermal deformation of geothermal reservoir rocks increased with increasing temperature, and the thermal deformation increased with increasing mineral particle size. Interestingly, alterations in thermal conductivity did not significantly impact the heat extraction performance of reservoirs. However, an increase in the specific heat capacity of rocks could increase the production temperature, extend the lifespan of geothermal reservoirs, and reduce differential pressure between production and injection wells. These findings provide insights into the design and construction of geothermal projects and contribute to advancing research on rock thermal properties.</p>