Cauda Cervi has been used as a nourishing invigorant in China for a long time. As recorded, the origins of Cauda Cervi are the dried tails of Cervus elaphus Linnaeus and Cervus nippon Temminck. In addition, Cervus albirostris Przewalski and Cervus unicolor Kerr are also used in some regions. Hair grows periodically and has high biological stability, which allows it to be used as specific markers for certain species. In order to differentiate four species of Cauda Cervi, microscopic characteristics of remnant hair were observed. Digital parameters such as the diameter of the hair shaft, medulla index and vein distance of the hair cuticle were compiled. It was shown that the method is convenient and feasible.