Abstract: Polysaccharide refers to a carbohydrate with complex and huge molecular structure.It is formed by dehydration with more than 10 monosaccharide molecules.Different types of polysaccharides have unique physi-chemical properties and biological activities.And they are closely related to polysaccharide's structure.In order to improve the performance of polysaccharides,researchers often modify polysaccharide structure in different ways.This paper reviewed some progresses of the research on polysaccharide modification from both domestic and overseas.