Abstract: In this paper the differences between V₂O₅/SiO₂ and V₂O₅-MoO₃/SiO₂ in activity of providing activated oxygen and the numbers and distribution of V⁴⁺ cations were investigated by measuring magnetic susceptibilities and irreversible adsorption amounts of catalysts and testing the catalytic activity with the flowing method.The different catalytic properties for hydrogenation of cyclohcxene and dehydrogenation of cyclohexane were discussed also.The information was drawn by the view point of the theory of corresponding structure of surface groups of catalyst.The results indicate that promoter MoO₃ increases the activity of providing oxygen,and the numbers of V⁴⁺ cation of V₂O₅-based catalyst and the probability of forming V⁴⁺ cation groups.The different influece on V₂O₅-based catalst by MoO₃ and P₂O₅ was also discussed.