Breast cancer ranks second in the list of most common cancers among women and brings the double burden of economy and health to women. Therefore, it is an urgent and necessary task to study the pathogenic mechanism and the treatment of breast cancer. Glycoprotein hormone is a kind of hormones to promote the growth and the development of cell and stanniocalcin 2 (STC2) is one of them. Research has shown us a various expression of SCT2 in organs and tissues and it can regulate many different pathological and physiological processes. In addition, there are a lot of previous studies that indicated a close correlation between STC2 and the development and metastasis of many cancers, which infers STC2 can serve as biomarker of certain cancers. Until now, the effects of STC2 on breast cancer have been studied widely, but research findings demonstrated two different views, one view is that STC2 plays an oncogenic role and the other is the opposite. In this paper, it will summarize and evaluate the research data and results about mammalian STC2 on breast cancer.