The paper mainly researched the properties of polyphenoloxidase (PPO) extracted from Huang - hua pear. It studied the PPO activities with spectrophotometer using catechol as substrate in different pH, temperature, enzyme concentrations, substrate concentrations and inhibitors. The results showed that there existed isoenzyme in Huanghua pear PPO and its optimal pH and temperature was 6. 0 and 251. At the same time, the browning inhibitory effects of ascorbic acid, citric acid, sodium sulfite and L - cysteine on PPO were also studied.