In the paper,we determined the inhibition rate of oleuropein on mushroom tyrosinase and tyrosinase in mouse B16 melanoma cells,analyzed the inhibition mechanism and type of oleuropein on mushroom tyrosinase,in order to evaluate its inhibitory effect on tyrosinase.The results showed that oleuropein had a significant inhibitory effect on tyrosinase activity in mouse B16 melanoma cells,and the inhibition rates of 100 and 200 μmol/L oleuropein on tyrosinase activity in B16 cells were 8.96%±2.53% and 33.41%±3.74%,respectively.Oleuropein has a certain inhibitory activity on mushroom tyrosinase,and its IC₅₀ is 0.210 mmol/L.The kinetic results showed that the inhibitory effect of oleuropein on mushroom tyrosinase was reversible non-competitive inhibition.In summary,oleuropein had a strong inhibitory effect on tyrosinase B16 cells and mushroom tyrosinase.The experimental results can provide a certain experimental and theoretical basis for the development of oleuropein as a whitening raw material.