The catalyst reactivity of Horseradish peroxidase was enhanced in the presence of β- cyclodextrin. During this course, β- cyclodextrin played a role of stabilizing the intermediates of HRP The results have been investigated using spectra and calculation. The catalyst reactivity of Horseradish peroxidase was enhanced in the presence of β-cyclodextrin. During this course, β-cyclodextrin played a role of stabilizing the intermediates of HRP The results have been investigated using spectra and calculation.