Abstract：Sandstone specimen is adopted to conduct test，and all of the homogeneity of specimen and the law of ultrasonic wave and porosity are studied before and after high temperature. Through the experimental study on the law of ultrasonic wave and porosity，the law of effect of temperature on sandstone damage is obtained. The result shows that the ultrasonic velocity increases except when the temperature is 200 ℃；the ultrasonic velocity will decrease when the temperature increases；the porosity will increase as the temperature increases. The two facts show that sandstone specimen is damaged after high temperature. The relation between ultrasonic velocity and damage factor is obtained，and the damage factor will increase as the temperature increases.
