The invention relates to the field of biomedicine detection, and provides a breast cancer marker which comprises at least one of glycoproteins such as serum transferrin with end N-acetylglucosamine sugar, plasma protease C1 inhibiting factors with end N-acetylglucosamine sugar and serine protease inhibitors B4 with end N-acetylglucosamine sugar. The quantity of any one, two or all of the glycoproteins in samples to be detected is detected, the breast cancer marker can judge or help to judge occurrence and/or development of breast cancers, and single or any combination of the glycoproteins canserve as markers for screening or auxiliary screening diagnosis of the breast cancers.