Abstract: Dextranase can specifically hydrolyze the α-1,6 glycosidic bond in dextran, reduce the viscosity of sugarcane juice, prevent the blockage of the instrument, and increase the recovery and quality of the target product. Dextranase degrades dextran and produces oligosaccharides such as isomaltose and isomaltotriose. These oligosaccharides are not digested and absorbed by human body, which can directly enter the large intestine and selectively proliferate beneficial bacteria such as Bifidobacterium. They have the effects of moistening intestine, promoting the absorption of mineral elements and enhancing immunity. Based on the research progress at home and abroad, the article reviews the structure of dextranase, dextranase production strains, dextranase enzyme activity and improvement technology of enzymatic properties. It is found that traditional mutagenesis technology and optimization of fermentation conditions can improve dextranase to a certain extent. Through the construction of genetically engineered bacteria, the heterologous expression level of dextranase can be effectively improved, combined with enzyme immobilization technology to improve the stability and recovery rate of the enzyme under unfavorable conditions. It is widely used in oligosaccharide preparation and sugar industry. This paper provides a reference for the research direction of late dextranase.