Protamines are a group of native polycationic antimicrobial peptides, which have a broad range of antimicrobial activity. Protamines inhibit or kill bacteria by destroying their cell wall, cell membrane and changing permeability of cytoplasm membrane. While protamine inhibit or kill bacteria, bacteria are induced a variety of mechanisms to resist it. Several physical and chemical factors, such as temperature, pH, cations and EDTA, can affect protamine's inhibitory potency to bacteria. Because protamines have many advantages in antimicrobial activity, they have been developed a kind of promising food preservative presently.