Maximum range must be periodically inspected,because it is a combination property for evaluating ranging performance of laser range finder.At the present time,measuring the range of actual target at the maximum range is restricted by conditions of weather and target,light extinction method also hard to operate because it needs to set or measure the real-time gain of laser receiving and processing circuit.At the meantime,there are enough methods to measure key parameters of laser range finder such as laser emitting energy,laser beam diffuse angle,deviation angle of optical axis,minimum detectable laser power,etc.So we can use these measuring results to evaluate whether the maximum range of laser range finder reaches desired impact.If we acquire accurate representation about laser energy distribution of specific-type laser range finders,theoretical formula for accurately evaluating maximum range can be given,then whether the maximum range reaches desired impact can be decided by measuring key parameters of laser range finder.