Abstract:Abstract：Chitin and its derivatives are very valuable natural polymers.Due to its film forming，wire drawing，non-toxicity，biocompatibility and other properties，it has been used in various fields of human activities.In recent years，domestic research efforts have been increased，but it is still far from enough.The main preparation methods of chitin/chitosan，including traditional chemical method，enzymatic method，microbial fermentation method and several new extraction methods，were reviewed.The application of chitin，chitosan and its derivatives in industry，food，cosmetics and other fields was introduced in order to help industrialization later.