Chitosan is deacetylated chitin, chemically named polyb-(1-4)-2-amino-2-deoxyl-D-glucosamine It is insouble in water,but soluble in diute acid and cna be taken up in the human body. chitosan is primary derivitive of chitin. it`s chemical structureis unique highpolymer of the basicpolysaccharide with positive ion and have special bioactivity, physical chemisal quality. there are specific properties, suchasadsorption,spinning,flocculence,decomposad ility,hygroscopicity and increasing immunities,decreasing the blood pressure,depress the fat and sugar of the blood,inhibit Acid,enhancing stomachic, action, promoting ulcer cure function, thus the chitosan open up to applied domains greatly. According to various viscosity, Chitosan has varied applications.