Abstract: In order to lighten weight of a laser rangefinder and improve the efficiency of optical alignment,a rotary dual-wedge pair was designed to align the optical axes.The mathematical model of the optical axis parallel deviation and the dual-wedge rotary angle was established,and the corresponding formula was derived.With a dual-wedge pair applied in a photoelectric fire control system of a light-weight weapon,the correction accuracy reached 0.1mrad.Experimental results indicate that this method is suitable to miniature the volume and weight,eliminate the influence of environment such as the temperature,shock.It is convenient for alignment and maintenance.