Abstract: Effect of CO2 pressure, temperature and time on activity of polyphenol oxidase were investigated, and the inactivation conditions for polyphenol oxidase of banana pulp treated by high pressure carbon dioxide were also optimized using quadratic orthogonal rotation combination design.Results showed that the influence sequence of the technological conditions on the activity of polyphenol oxidase was temperature > treatment time > the pressure of CO2 . The optimum conditions for polyphenol oxidase inactivation of banana pulp by high pressure carbon dioxide were 19MPa at 60℃ for 50min, and the residual activity of polyphenol oxidase in optimum conditions was 0.9%.