The catalytic properties of horseradish peroxidase(HRP) in the dioxane aqueous were studied. The enzyme has higher catalytic activity for the phenols with para substituted active group. The catalytic activity of HRP is also highly correlated with the steric hindrance of the substrate and decreases with the increase of the concentration of the dioxane. In dioxane aqueous
the optimum pH of HRP catalysis ranges from 5.6 to 6.2
and the catalytic activity of HRP at 60 ℃ is the highest. The fluorescence intensity of HRP was found to be the highest in φ=70% dioxane solution. The inhibition of hydrogen peroxide for HRP decreases with the increasing of the concentration of dioxane.