Abstract: Fresh tea juice is extremely prone to browning during its storage for high content of polyphenols. In this study, influences of different temperature, pH and inhibitors with different concentrations on the activities of polyphenol oxidase were analyzed by using the method of spectrophotometry. The results showed that activities of polyphenol oxidase in fresh tea juice maintained at high level within 25~40, activities of polyphenol oxidase in fresh tea juice dropped rapidly after its temperature exceeded 40. Activities of polyphenol oxidase in fresh tea juice were relatively stable when the pH was between 5.5 and 6.5, and decreased rapidly after pH exceeded 6.5. Citric acid and NaHSO3 with different concentrations could obviously inhibit the activities of polyphenol oxidase in fresh tea juice, and 0.5% citric acid had the best effect on inhibiting the activities of polyphenol oxidase in fresh tea juice.