Abstract: During the preparation of different deacetylated degrees of chitin from 4.5% to 95%, it has been found that the deacetylation rate varied with the pieces size of chitin and the reaction time. The chitosan membranes prepared by coating its solution on a glass plate and drying it at different temperatures show different crystal structures and mechanical properties under the measurement of PLM, XRDand DSC. XRDmeasurement also gives the difference between chitin and chitosan as well as the similarity of chitin films separately coated from crab chitin, silkworm chitin and squid chitin. The crystal cell of chitosan fiber is determined as a =0.987 nm, b =0.924 nm, c =1.031 nm and β =83.29 °.

Key words: Chitin, Chitosan, Crystallinity, X-ray diffraction, Mechanical property