Abstract: Ultrasonic guided wave detection technology has the advantages of long detection distance and high efficiency. It is very suitable for the detection of round pipe structures such as gun barrel, and has outstanding military application value and prospects. In this paper, the theory of ultrasonic guided wave of circular tube is first deduced, and the basic principle of detection is described with a certain type of gun barrel as the research object. The dispersion curve is plotted by numerical calculation method. The frequency of the guided wave is optimized by analyzing its dispersion characteristics, and the optimal detection frequency range is preliminarily obtained. Secondly, the relationship between the type selection, number and distribution mode of sensors and the guided wave propagation characteristics are studied. Experiments show that the best frequency range for guided wave detection is 0~300kHz, and the guided wave bending mode is generally not suitable for detection mode. The increase in the number of sensors not only enhances the strength of the excitation signal, but also effectively suppresses the dispersion of guided waves in the gun barrel.