Lysozyme is a glycoside hydrolase, which is composed of 18 kinds of 129 amino acid residues and has 4 S-S bonds. The substrate specificity of lysozyme is very strong, and the substrates of lysozyme from different sources are different. Lysozyme is ubiquitous in various tissues and secretions of humans and animals, as well as in some plants and microorganisms. It can dissolve the cell wall of Gram-positive bacteria and has a strong killing effect on it. It is used for food preservation (especially Cheese, sake production), medicine (tablets, capsules, eye drops, throat lotion), and scientific research have broad prospects.