Abstract: Polysaccharide are important medicinal active ingredients.They are likely to have a higher activity or generate new activity after chemical modification.This paper will conduct a study in this field,expounding sulfation,phosphorylation,carboxymethylation,alkylation and acylation on polysaccharide and their influence on biological activities,and have an outlook on their application prospect.

Key words: polysaccharide, chemical modification, biological activities, research progress