Abstract:Chitin deacetylase（CDA） is an enzyme which can catalyze deacetylase reaction in chitin generating chitosan. Chitosan has several excellent properties， such as antibacterial， anticancer， and antiviral， with wide application prospect in the medicine， chemical， and food industries. The research situation of CDA was re－ viewed， including enzymatic properties， catalytic mechanism， the method of separation and purification， etc. Furthermore， the screening methods and process of CDA producing strains were briefly introduced， and the fu－ ture research direction of CDA was prospected.