Abstract: The chemical modification, preparation by fermentation process, biological modification and structure-activity relationship of Poria cocos polysaccharide were reviewed. Sclerotium of P. cocos is a kind of famous and precious traditional Chinese medicinal materials that have been widely applied in the field of medicine, food, etc, and it’s main ingredients is P. cocos polysaccharides. Most P. cocos polysaccharides are alkali soluble polysaccharides which are not dissoluble in water. It has low bio-activity and needs to carry out molecular modification. Nowadays, the bio-activities of P. cocos polysaccharide by chemical modification have been identified higher than water-soluble P. cocos polysaccharide, and show new bio-activity. But chemical modification exists some environmental problems of chemicals agents remaining, high costs and so on. Moreover, the material supply of sclerotium of P. cocos is subjected to the forest resource. P. cocos polysaccharide could not only be synthesized from the original simple matrix by fermentation process, but also could obtain the polysaccharide by the directional modification which the original activity shows to be improved or get new activity. Biological modification of P. cocos polysaccharide is to control its structure and properties in the fermentation process by adding material. The modification methods and structure-activity relationship of P. cocos polysaccharides need further study.

Key words: Poria cocos polysaccharides, chemical modification, biological modification, structure-activity relationship