The kinetics of inhibitory effect of total ginkgolic acids ( C13:0, C15:1, C17:2, C15:0, C17:1 ) on the monophenolase and diphenolase activity of mushroom tyrosinase was studied. The effect on catalytic reaction of tyrosinase process, the enzyme activity inhibition rate and inhibitory kinetic parameters of total ginkgolic acids were tested at 28 ℃, pH = 6.8 Na2HPO4-NaH2PO4 buffer system. It was found that total ginkgolic acids efficiently inhibits both monophenolase and diphenolase activities of mushroom tyrosinase under experiment conditions. Concentrations of total ginkgolic acids leading to 50% rate inhibition (IC50) on monophenolase and diphenolase activity were calculated to be 0.03 g?L-1 and 0.20 g?L-1 respectively. The presence of total ginkgolic acids also prolongs the lag period in the oxidation process of L-tyrosine via tyrosinase. A reversible inhibition of diphenolase by total ginkgolic acids has been found, indicating that the inhibitor binds the enzyme reversibly other than reacts with it destructively. The Lineweaver-Burk plot demonstrates a competitive behavior of total ginkgolic acids in the tyrosinase oxidation of L-DOPA, with inhibition constant KI at 75.20 ug/ml.