Abstract: The optimum condition for determination of polyphenol oxidase(PPO) from cabbage and the induction of polyphenol oxidase by insecticides and Plutella xylostella and Myzus persicae infest were investigated. The optimum pH value and temperature are 6.4 and 55℃ for assay of polyphenol oxidase activities respectively in cabbage. Ethanol and acetone exhibit the activation to polyphenol oxidese from cabbage. α-cypermethrin, methomyl and phoxim, and the infesting of Plutella xylostella and Myzus persicae can influence the specific activity of polyphenol oxidase in cabbage.