In this paper, an ideal structural model and a scientific and practical mathematical model of high temperature permeability testing technology were established based on the formula of gas permeability at room temperature according to Darcy’s equation and Forchheimer equation and combined with the basic law of gas mechanics and the resistance loss of gas movement process at high temperatures. Through a gas heater, the safe heating of gas from room temperature to the test temperature was realized; the pressure sealing of high temperature permeability test technology was studied using high temperature resistant flexible material instead of silica gel material and combining preloading with system expansion and continuous loading. Based on the above research, a high temperature gas permeability tester for refractories has been developed and the test temperature can be up to 1 000 ℃. The equipment was applied to research refractories, showing well using effects.