Abstract: The phytic acid in wheat bran was extracted by solution of hydrochloric acid. Based on the single factor experiment test, the extract conditions, such as extraction time, temperature, hydrochloric acid concentration and ratio of solid to liquid were investigated and optimized by response surface methodology. Then a quadratic polynomial mathematical model of phytic acid extraction was established. The antimicrobial spectrum and the minimum inhibition concentration ( MIC) of Escherichia coli, Staphyloccocus aureus, Bacillus subtilis and Salmonella were studied by means of oxford- cup tests.Also the antimicrobial effect of phytic acid on different concentrations, metal cations and concentration, temperature and organic solvents were discussed. The results indicated that the optimal conditions were as follows: extraction time 2.2h, extraction temperature 40℃, 1.2mol / L hydrochloric acid solution, ratio of solid to liquid 1∶22 ( g / m L) .Based on the optimal conditions, the yield of phytic acid was 1.215%. The phytic acid of wheat bran could effectively inhibit the growth of bacteria. The MIC were 2.17, 2.89, 3.61, 3.61μg / m L respectively.The antimicrobial effect becomes stronger with the concentration increasing.The antimicrobial effect of phytic acid was weakened by combination with 100, 200, 300 mmol / L solution of Na Cl, KCl, Mg Cl2, Ca Cl2 and 10% ( v/v) ethyl alcohol, proplene glycol, glycerine, the antimicrobial effect of phytic acid was no difference when temperature was 0, 65, 121℃.