Abstract: The influence of the one-stage single-lens optical system on the divergence angle of Gaussian laser beam is analyzed theoretically. The semiconductor laser in laser fuze was collimated with a plane-convex lens, and the result of the collimation met the requirement of the laser fuze. The divergence angle of light beam was measured with the method of CCD imaging and computed by second moment method. In the experiment, the horizontal divergence angle of 7.03°and the vertical divergence angle of 0.69° were obtained. Therefore, it is verified that the collimating system satisfies the specifications of θx＜10° and θy＜1°required by laser fuze.