Abstract: In order to enhance the production of alginate lyase by Photosbacterium phosphoreum, response surface methodology was applied to optimize the culture medium. Based on the single factor experiment, a fractional factorial design was used to investigate the main factors affecting alginate lyase yield. The results showed that two factors played important roles in the production of alginate lyase.Central composite design and response surface analysis were applied to establish a second-order regression equation model for the yield of alginate lyase. At last, the optimal fermentation medium were obtained by response surface analysis as follows: glucose 1.211 g, beef extract 0.2 g, KCl 0.5 g, FeSO₄·7H₂O 0.05 g, K₂HPO₄ 0.02 g, MgSO₄·7H₂O 0.005 g, initial pH8.6.Under the optimal conditions, the activity of alginate lyase reached 69.05 U/m L.By optimization of culture medium, production of alginate lyase was improved 14.5 times compared to basic culture medium.In conclusion, the optimized process has good reliability.