Abstract: A series of titania-alumina mixed oxide with different amount of γ-Al₂O₃were prepared by sol-gel methods, which were loaded by V₂O₅ and WO₃ to obtain several SCR catalysts. Surface properties of those samples were studied by various characterizations techniques, like XRD, BET, H₂-TPR and HRTEM. The catalytic performance for the selective catalytic reduction of NO with NH₃(NH₃-SCR)and the effect of SO₂ in the simulated smog on the catalytic activity were investigated as well. It is found that the synergy between γ-Al₂O₃ and TiO₂ can improve effectively the catalytic performance of V₂O₅-WO₃/TiO₂-γ-Al₂O₃ catalysts effectively and broaden the temperature window of SCR activity as well as strengthen the resistance to SO₂ poisoning. In particular, the V₂O₅-WO₃/TiO₂-15% γ-Al₂O₃ sample exhibited 80% NO conversion in the wide temperature range of 310~460 ℃.All the characterization results show that γ-Al₂O₃ is in a well-dispersed state on the surface of TiO₂; the composite support has a large specific surface area and the binary oxide possesses a comparatively strong redox property.