A simple method of trypsin/collagenase I alternative digestion and iterative culture flask adherence to discard fibroblasts for bovine mammary cell culture was established in this study. By immunohistochemistry, flow cytometry, western blot, Electron microscopy analysis, the characteristics of bovine mammary cells were investigated in vitro. Effect of hyperthermia on the cell ultrastructures was also observed. The results showed that the mammary cells were diploid epithelia with intact 30 pairs chromatins, which could secrete alpha-casein into the medium. After exposed to hyperthermia, the cell condensed chromatin like crescent on the nuclei verges, mitochondria occurred expansion and vacuolization, and apoptotic bodies appeared, which suggested that heat stress could induce apoptosis of the mammary epithelia.