In order to establish the quantitative evaluation model of reservoir permeability changing with the change of temperature and pore pressure in the process of oil and gas exploitation, assuming that the rock only produces elastic deformation, according to the elastic mechanics theory of porous media, the stress-strain relationship of rock pore volume and size is deduced; then the pipe flow is used to simulate seepage, and the permeability changing with the change of temperature and pore pressure is obtained according to the Kozeny-Carman equation Quantitative calculation model. In view of the problems existing in conventional permeability testing, the core mechanics and permeability synchronization experiments were carried out by improving the experimental method and simulating the real reservoir temperature and pressure conditions. The results show that the permeability loss calculated by the model in this paper is in good agreement with the experimental test results; the model is suitable for the quantitative calculation of permeability of tight rock with undeveloped fracture in the range of elastic deformation; with oil and gas production, the permeability decreases due to the decrease of pore pressure; the permeability increases due to the decrease of formation temperature; the influence of the two aspects on permeability is mutually offset The permeability change of reservoir rock caused by the change of temperature and pore pressure is very small, generally not more than ± 2%.