Abstract: Based on the theory of perspective projection and the theory of spatial analytic geometry a new modeling method of laser auto-collimation angle measurement is proposed. Through analyzing on the center of ellipse track of spot and reference zero of system, a mathematical model of this distortion error of the reference zero is established. Meanwhile, the simulation is done and some conclusions about the distortion error are drawn. An available theoretical reference for the system calibration of laser auto-collimation angle measurement or the obtainment of the reference zero is proved. Thus it is really significant in theory and is valuable in engineering applications.

Key words: Angle measurement model, Distortion error, Laser auto-collimation, Perspective projection transformation, Simulation