Aiming at the measurement technology and automatic detection of the rifling inside the gun barrel, a method of precision measurement data compensation is proposed. The measurement system of artillery bore inspection robot is set up. The laser range finder was used to measure the inner diameter of the yin-yang line of the gun barrel, and the PSD laser position sensor was used to measure the eccentric distance between the axis of the gun barrel and the axis of the measuring system. The causes of the measurement error were analyzed, and the accuracy compensation algorithm and error compensation formula based on the vector trigonometry method were derived. The results show that the measurement and compensation method is effective, and it solves the problem of the error caused by the misalignment of the gun bore axis and the robot rotation center.