Abstract: An ultrasonic thickness measurement system of high-temperature industrial pipe is developed which embeds the experimentally derived two-dimensional function V=f(T, H0) among temperature, thickness and sound velocity into the high-temperature thickness gauge, based on the analysis of the inhomogeneity of sound velocity in the high-temperature wall thickness direction and the effect of industrial pipe temperature and wall thickness on ultrasonic thickness measurement. The method is combined with the field portable thickness gauge for data conversion and sound velocity verification quickly according to the wall temperature and thickness. The measurement data is checked and the accuracy is greatly improved with the application of the algorithm.