Tyrosinase (EC 1.14.18.1), which belongs to a protein family having the catalytic center formed by dinudear copper, occurs in prokaryotic and eukaryotic organisms.It is a key enzyme in pigment biosynthesis of organisms.The tyrosinase inhibitors can be used in cosmetics, fruit preserver and pesticide.Several benzaldehydes thiosemicarbazone derivatives are synthesized as inhibitors of tyrosinase for the study of inhibitory effect on tyrosinase.First, the effects of benzaldehyde thiosemicarbazone derivatives on the monophenolase and diphenolase activity of mushroom tyrosinase have been investigated.The results show that these compounds can potently inhibit both monophenolase activity and diphenolase activity of mushroom tyrosinase.The IC50 values and kinetics constants are estimated, respectively.And the inhibitory mechanisms of compounds on monophenolase and diphenolase activity of mushroom tyrosinase are elucidated.Then, the inhibitory effects of the compounds on free-cell tyrosinase and tyrosinase from melanoma cell are studied.And, the results show that the compounds can also effectively inhibit the activity of tyrosinase from different organisms.