Tyrosinase is a copper-containing enzyme,Which is responsible for skin,eye,inner ear,and hair melanization.Tyrosinase activators have become increasing important in food,agricultural,pharmaceutical,cosmetic,and pesticide industries.In this paper,4-hydroxyphenylacetic acid was studied to active the diphenolase activity oftyrosinase.The results showed that the 4-hydroxyphenylacetic acid had strong activation effects on diophenolase activity.Moreover,when the concentration of 4-hydroxyphenylacetic acid reached 0.7 mM,the activation ratio was determined to be 108%.4-Hydroxyphenylacetic acid is simple and easy to gain,furthermore,seems to be a reasonably good candidate for a diphenolase positive effector.