Abstract: Protamine is a polycationic peptide found in the testis tissue of different fish species, being a alkaline protein and rich in arginine. Protaimine has been widely applied in medical and health field for it possesses several functions such as it could promote the proliferation and development of cells, enhance the functions of liver, inhibit the growth and reproduction of tumor. In addition, it has such a significant antimicrobial activity that it can be developed as a natural preservative. Therefore, the article elaborated the extraction and purification processes of protamine, based on analyzing the basic characteristics of protamine, and reviewed the applications of protaimine in food, medical fields and molecular level respectively.