A self-aligning technique of mobile lidar optics was developed, which adopted CCD camera and image processing to measure laser beam direction departure from the axis of receiver optics. It used a 2D motorized optical mounts to change the direction of laser beam. The computer presides over monitoring the alignment and adjusting the direction of laser beam. The measurements in testing system in the lab indicate that, the spending time to accomplish self-aligning has not exceed 40 s normally, when the aligning error presets to 40 μrad.