Abstract: The fermentation conditions of marine Arthrobacter protophormiae CDA2-2-2 were optimized to enhance the production of chitin deacetylase. Different process variables such as carbon sources, nitrogen sources, temperature, metal ions, time, volume, initial pH, rotate speed, and inoculum size were evaluated by one parameter at-a-time strategy. A significant influence of MgSO₄, fermentation temperature and glucose on chitin deacetylase production was noted with Plackett-Burman design. Then, a three-level Box-Behnken design was employed to optimize the medium composition and culture conditions to produce the chitin deacetylase in shake-flask. Using this methodology, the quadratic regression model of producing chitin deacetylase was built and the optimal combinations of media constituents and culture conditions for maximum chitin deacetylase production were determined as MgSO₄ 0.01%, fermentation temperature 38 ℃, glucose 0.57%. Chitin deacetylase production obtained experimentally coincident with the predicted value and the model was proven to be adequate. The optimization of these parameters in flask experiments allowed us to increase the production of chitin deacetylase to 14.58 U/mL, which was increased by 2.5 times than that of before optimization. These results support the potential use of A. protophormiae CDA2-2-2 to produce chitin deacetylase, which would be applied to prepare chitosan with enzymatic deacetylation route.