In order to study the effect of high temperature on the mechanical properties and thermal conductivity of geopolymer mortar, five temperatures, 25°C, 200°C, 400°C, 600°C, and 800°C, were set up with temperature as a variable for conventional thermal conductivity tests and uniaxial pressure tests. . The thermal conductivity, stress-strain full curve, compressive strength, peak strain, tangent modulus and other parameters were obtained in the test. The influence law of its mechanical properties and thermal conductivity, and the high temperature damage model of geopolymer mortar is established. The results show that: (1) with the increase of temperature, the thermal conductivity of geopolymer mortar shows a decreasing trend. When the temperature is 200℃, the thermal conductivity of geopolymer mortar decreases significantly compared with other temperatures; (2) the high temperature makes the ground The mechanical properties of polymer mortar continue to decrease with the increase of temperature, and with the increase of temperature, the effect of high temperature deterioration becomes more and more significant, and the strength decreases rapidly; (3) high temperature will cause the internal cracks of geopolymer mortar to gradually increase, CSH The cementitious material decreases, and the CSH cementitious material basically disappears when the temperature is 600 °C, and the solid-phase reaction occurs at 800 °C to form mayenite, and the small cracks inside the mortar are transformed into large through-type cracks; (4) The high temperature of geopolymer mortar was established. damage model.