Abstract: During the coupled thermal-hydro-mechanical analysis of porous media,the porosity and viscosity of porous water are the main factors affecting the permeability of the rock mass.Based on the variation law of porosity and viscosity of porous water undertaking loads,a method of stress-dependent porosity and temperature-dependent viscosity of porous water is developed during the numerical analysis.To investigate the influence of mechanical boundary conditions on the thermal stress,a comparison of the results between displacement boundary and stress boundary is made.The study indicates that the values of thermal stress and pore pressure obtained by stress boundary are smaller than those by displacement boundary.The calculated values of pore pressure taking nonlinear seepage behavior into account are closer to the measured ones.