Active imaging LADAR (Laser Detection And Ranging) stands out from other passive imaging systems for its function of acquiring range image of targets. Compared with traditional optical image, range image has more particular statistical characteristics, it can obviously show multi-peak structures when multiple targets exist in the range image. Target Extraction of range image could be realized by extracting peaks of its stat-histogram; and targets could be classified by the size and rectangle degree obtained by the use of minimum enclosing rectangle. Processing a real range image by using this method has obtained the anticipated result.