Aiming at such problems as low accuracy, low efficiency, more operators and disperse structure existing in the measurement of deviation angle of guns using the method in the national military standard, a novel method for the measurement of gun deviation angles is proposed. Based on the principle of measuring three-dimensional (3D) coordinates of a spatial point by the 3D laser radar, standard target balls adhering to the gun barrel are used to solve two spatial linear equations before and after gun adjusting through measuring the spherical coordinates of spatial points of standard target balls. After the projection of space vectors, the equations are transformed to solution of linear equations on the projection plane, thus the gun deviation angle is calculated, and the measurement accuracy is calculated and analyzed by differentiation. The principle and measurement process of the method is compared to that in the national military standard, and the experimental data show that the efficiency and accuracy is improved notably when the proposed method is adopted to measure the gun deviation angle.