In these years, with the wide application of collagen in many fields as biomaterial, the market for collagen is increasing. Traditional production methods of collagen can not satisfy the increasing demands. As the transgenic technique developes, using transgenic bioreactor to produce collagen becomes the key to solve this problem，this research is hot spot. Transgenic mammary gland reactor possesses more advantages in producing highly-complex protein than other bioreactors. Proteins expression in mammary gland after translation and elaboration is very similar to their native counterpart in structure and function. In this test, the human COL1A1 (typeI collagen, α1-chain) gene fragment was successfully subcloned it into mammary gland specific vector. Finally, the Holstein cow fetal fibroblast cells were successfully transfected with this recombinant construct. 22 Holstein cow fetal fibroblast cell lines was established. The cells were transfected by the recombinant mammry specific construct. We obtained 16 transgenic cell line frome 22 cell line by PCR with verification primer. This test could be used to correctly evaluated expression efficiency of mammary specific construct. Our test underlied the high expression of recombinant proteins in mammary gland.