Abstract: There is a huge amount of chitin resources in the marine environment. The marine microorganisms based on bacteria can produce chitinase to hydrolyze long-chain chitin to usable monomers, maintaining a balance of carbon and nitrogen cycles with ecological significance. Meanwhile, the industrial use of chitinase to prepare N-acetyl-D-glucosamine and chitin oligosaccharides has great application value. To date, researchers have identified chitinases produced by more than 30 marine bacteria. This article focuses on the structure and source of marine chitin, the mode of action of chitinase and the catalytic properties of chitinase derived from marine bacteria, and analyzes the application of chitinase in agriculture, medicine and food. Chitinase is expected to become a new type of industrial enzyme.