Polysaccharides are the main components in food and have a wide range of physiological functions. However， some natural polysaccharides are limited in application due to large molecular weight， poor solubility and unsatisfactory function. Fermentation is a traditional processing method to improve the nutritional quality of food， besides， it is a promising biological modification method， which has been more and more widely used in the structural modification of natural products. During the fermentation process， microorganisms secrete carbohydrate active enzymes to degrade and convert polysaccharides to lower molecular weight polysaccharides， oligosaccharides and monosaccharides， and also change their biological activities. This review focused on the dominant bacteria to polysaccharides utilization in fermented foods and their effects on the content， structure and bioactivities of polysaccharides in raw materials， thus giving an insight into green transformation of polysaccharides and providing ideas for future research in related fields.