Natural polysaccharides have shown the advantages of low cost， wide application， high biocompatibility and degradability. They can be used as nano delivery carriers of functional factors to improve the bioavailability and physicochemical stability of functional factors. In order to provide reference for the efficient preparation of polysaccharide based nanocarriers with biological functions. The origin of nanotechnology and the advantages of polysaccharide based nanocarriers were summarized， as well as the preparation methods， formation mechanism， structural characteristics， encapsulation efficiency， release rate of different types of polysaccharide based nanocarriers. The potential problems and application prospects of polysaccharide based nanocarriers were discussed in functional food research.