The laser rangefinder is an instrument which can measure the distance of the target by using a certain parameter of the modulated laser. The measuring range of laser rangefinder is 40-200m. The laser rangefinder is to shoot a short pulse laser beam or a series of pulse laser beams to the target when it is working. The laser beam reflected by the target is received by the photoelectric element. The timer measures the time from the launch to the reception of the laser beam and calculates the distance from the observer to the target.