On the basis of thermodynamic theory, and with full consideration of the impact of defects, the change law of thermal stress in defect of granite was researched under the action of temperature.The local stress in granite defects was derived as a function of temperature loading rate, initial temperature, final temperature and defect.With consideriation of the role of the thermodynamic parameters, such as temperature, free energy and entropy in the damage evolution of granite, and on the basis of the energy theory, the function of energy release rate was deduced.By using thermal elastoplastic numerical model, the numerical simulations of the thermal stress and thermal energy in a single crack defect granite in the process of temperature load was conducted.The change curves of thermal stress were obtained.The results and the theoretically derived results are basically identical.The results will provide important theoretical basis for the research of high temperature fracture rock engineering.