0.5%Pt-K/γ-Al2O3 catalysts for the synthesis of o-phenylphenol(OPP) from o-cyclohexenyl-cyclohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K2SO4 to Pt/γ-Al2O3 catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. The higher activity was obtained when Pt/γ-Al2O3 catalyst was calcined in nitrogen atmosphere at 400―500 °C and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h. 0.5% Pt-K / γ-Al2O3 catalysts for the synthesis of o-phenylphenol (OPP) from o-cyclohexenyl-cyclohexanone (dimer) dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K2SO4 to Pt / γ-Al2O3 catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. activity was obtained when Pt / γ-Al2O3 catalyst was calcined in nitrogen atmosphere at 400-500 ° C and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5% Pt-6% K2SO4 / γ-Al2O3 catalyst during the pilot scale test of 8000 h.