Abstract: As the tissue density and polyphenol oxidase (PPO) existing forms are greatly different between green banana and ripe banana. In this study, taking the specific activity of PPO as index, effect of some factors including buffer type, ionic strength, pH value, ratio of liquid to solid, PVPP, Tween 80, extraction time, extraction times on the extraction of PPO were studied and the best extraction conditions were 0.05 mol/L pH 6 phosphate buffer containing 5% PVPP and 1% Tween 80, liquid to solid ratio of 1.51 (V/W), homogenization at 10 000 r/min for 20 s, centrifugation at 10 000 r/min for 30 min at 4, extraction for two times, as the supernatant was crude enzyme, and the specific activity was 1 574.06 U/mg. As the tissue density and polyphenol oxidase (PPO) existing forms are greatly different between green banana and ripe banana. In this study, taking the specific activity of PPO as index, effect of some factors including buffer type, ionic strength, pH value, ratio of liquid to solid, PVPP, Tween 80, extraction time, extraction times on the extraction of PPO were studied and the best extraction conditions were 0.05 mol/L pH 6 phosphate buffer containing 5% PVPP and 1% Tween 80, liquid to solid ratio of 1.5颐1 (V/W), homogenization at 10 000 r/min for 20 s, centrifugation at 10 000 r/min for 30 min at 4益, extraction for two times, as the supernatant was crude enzyme, and the specific activity was 1 574.06 U/mg.