Abstract: β-mannanase belongs to glycoside hydrolases family and widely exists in plants,animals and microorganisms. Its main hydrolytic product is mannan-oligosaccharides(MOS). There are many kinds of mannanase from microorganisms and their activities are high,but most of them are low in safety. Lactic acid bacteria(LAB)mannanase has the advantages of few purification steps,easier extraction,and higher safety,so it has an important application prospect in food grade fields,including health products,feeds,beverages and other industries. In this paper,the enzyme production conditions,isolation and purification and enzymatic characteristics of natural LAB mannanase were introduced. The LAB recombinant expression of mannanase in recent years and its application in juice clarification and preparation of prebiotics MOS were briefly described,providing reference and basis for the basic research and development of mannanase from LAB.