Abstract: Aiming at the problem of pipe thickness measurement under high temperature in the petrochemical industry, this paper investigates factors affecting high temperature pipe thickness measurements based on ultrasonic spectrum, and develops an ultrasonic thickness measurement simulation system. In the simulation experiment, the influence of different thickness, different materials, different noise levels and different temperatures on the measurement results are discussed. In addition, the influence of different thickness measurement methods on the measurement of pipe thickness is compared. The experiment results show that the system can simulate the high temperature ultrasonic thickness measuring system and measure the high temperature pipe thickness.