Abstract: To study the effect of high temperature on strength of sandstone, the relationship between the physical and mechanical properties of sandstone and its temperature and confining pressure was studied by using XTR01 rock mechanics testing machine to carry out triaxial compression test of sandstone after high temperature treatment from 200 ℃ to 1 000 ℃. The results show that compressive strength and elastic modulus of sandstone increase as the temperature increases before 600 ℃, then decrease with the increasing temperature, and reach the maximum value at 600 ℃ and with the increasing of confining pressure, compressive strength and elastic modulus increases linearly. It is concluded that 600 ℃ is a threshold temperature.