【abstract】 Objective To study the comparetive histology of male reproductive system in five kinds of common laboratory animals, and to find out the similarities and differences among them to provide normal histologic controls for the basic research of the laboratory animal study. Methods Five kinds of animals, i.e., Kunming mice ,SD rats, Japanese big ear rabbit, Beagle and tree shrews, which all reaching sexual maturity and their quality all meeting the national quality standards of the laboratory animal inspection, were selected to undergo pathological anatomy, pathological slices –making, conventional HE staining, immunohistochemical staining after painless death for the research of the histological similarities and differences on the testicles, epididymis, prostate, seminal vesicle gland and penis among them under microscope. Results (1) The maximum number of plies of spermatogenic cells in seminiferous tubule is found in Japanese big ear rabbit, the maximum number of sperm counts is found in SD rat, and the thickest ply of albuginea is found in Beagle. (2) Differences are found in epididymis covering epithelium among the test animals, the epididymal epithelium of Japanese big ear rabbit is arranged in papillary and screen pipe structure, and its muscle layer is the thickest of all. (3) Different animal species varies in the size of prostate volume, Beagles have the biggest prostate volume and the most number of glands, while Kunming mice and Tree shrews have the minimum of that; The least smooth muscle amount is found in kunming mice, while The SD rats Rats and tree shrews have the most smooth muscle amount. (4) Seminal vesicle glands of the SD rats are obvious at its big volume and cystic, its epithelial cells have many branches and are connected into nets, its glandular cavity is filled with red secretion, while Beagle has no seminal vesicle gland at all.(5) Kunming mice , SD rats and beagle have penis bone,Kunming mice and SD rats have mucous glands wrapped around the penis bone with marrow cavity,while Beagle’s penis bone is make up of mature lamellar bone, without mucous glands and marrow cavity, and Beagle penis contains more thick wall vessel, sympathetic nerve plexus and fat cells.The penis of Kunming mice and SD rats contains preputial glands(serous gland and mixed gland respectively), which developed much in Kunming mice. (6) A handful of laboratory animals are attacked by inflammation, ulcers, calcification, hyperplasia of lymphoid follicles and some spontaneous lesions. Conclusion There are some histologic differences in the male reproductive system of laboratory animals, so this should be take into account in experiments and related pathology inspection of laboratory animals.