ephacryl S-300 gel filtration chromatography was used to purify Chitosan from Maggots shell.The Chitosan was identified as two fractions by HPLC analysis,the molecular weight was 230 and 620 kDa,respectively.The results indicated that Sephacryl S-300 chromatography was useful for purification of Chitosan.The two fractions was analyzed by infrared spectrum and X-ray,the results showed that both fractions had characteristic absorption peak of Chitosan functional group in the IR spectrum.Crystallinity degree of fraction one was low and the fraction two was high.