Abstract: The components of fermentation medium were optimized by response surface methodology to improve the production of bacteriocin of lactobacillus casei. Based on confirming significant factors through single factor experiment,the central composite design( CCD) principle and the response surface analysis were used to establish the quadratic polynomial regression equation prediction model to determine the suitable fermentation medium for the production of bacteriocin of lactobacillus casei.The optimized fermentation medium was composed( %) of 1.86 lactose,1.0 tryptone,3.02 ammonium citrate. Under this condition,the verifying test result of the bacteriostatic ring was 17.85 mm which was consistent with the theoretical value( 18.20mm) of the bacteriostatic ring.The performance of the bacteriostasis was improved significantly than that before optimization.