Tibetan sheep live in high altitude areas and possess good adaptability to high-altitude hypoxia. As the critical organs of spermatogenesis and sperm transportation, testicles are extremely sensitive to environment. The testicular and epididymal arterioles are regulated by the autonomic nervous system and control the blood flow in the entire microcirculation duct. Here, twenty testes of Tibetan sheep and Small-Tailed Han sheep were collected from their living areas including Qinghai and Gansu, respectively. The morphological characteristics of arterioles in testicular lobule and epididymides were investigated by using the blood perfusion technology and scanning electron microscopic method. The results demonstrated that arterioles of testicular lobule and epididymis exhibited a degree of curvature, and small arteries from the centripetal and centrifugal parts showed “dendritic” distribution（Fig. 1）. It was found that spiral of knot-like artery in Tibetan sheep showed tighter and more branches of small arteries than that in Small-Tailed Han sheep. The diameters of centripetal, Knot-like, centrifugal arteries and caput epididymal artery in Tibetan sheep were larger than those of Small-Tailed Han sheep (Table 1). Moreover, there were shallow imprints of the smooth muscles on the surface of testicular lobule and caput epididymis casts, but those in Small-Tailed Han sheep were deeper. Meanwhile there were more and intense precapillary constrictions in testicular lobule than those in Small-Tailed Han sheep (Fig. 2). The study suggested that the arteriole of testicular lobule and epididymis in Tibetan sheep contribute to vasoconstriction and sperm maturation, which became important anatomical characteristics for their adaptation to the plateau environment.