Abstract: The pose measurement of gun barrel is difficult in the precision analysis of self-propelled antiaircraft gun (SPAAG) fire control system. To solve this problem, a non-contact and direct measurement method based on monocular vision was proposed. A checked planar template was fixed on the gun barrel as a marker which is within the field of view of a camera. Both elevation angle and azimuth angle were measured. Firstly, the coordinates of corner points were obtained by using Harris corner detection algorithm to calibrate the camera, and the camera’s intrinsic parameters were obtained by solving the camera model. Then, combined with LSE algorithm, the extrinsic parameter matrix of the corresponding position was found according to the stability of solutions in PnP problem. Finally, based on the motion model of gun barrel and its position relative to the marker, two angles were figured out. Simulation and experiment results show that the method can measure the barrel pose easily and accurately.