Nitrogen　oxide(NOx)　emitted　from　stationary　and　mobile　sources　is　a　major　air　pollutant.　Selective　catalytic　reduction(SCR)　of　NOx　over　a　catalyst　is　a　main　technology　for　NOx　elimination.　Catalysts　used　for　practical　applications　would　be　deactivated　in　flue　containing　SO2.　In　this　work,　three　typical　commercial　catalysts　were　investigated　before　and　after　SO2　treatment.　The　catalysts　were　characterized　by　X-ray　diffraction(XRD),　X-ray　fluorescene(XRF),　temperature　programme　reduction(TPR),　temperature　programme　desorption(TPD)　and　diffuse　reflectance　Fourier　transform　infrared(DRIFT)　techniques.　Results　showed　that　SO2　treatment　significantly　influenced　the　performance　of　V2O5/TiO2　catalyst.　The　amount　of　V2O5　in　the　catalyst　primarily　affected　the　accumulation　of　sulfur　species　in　the　SO2　atmosphere.　The　performance　of　catalysts　with　small　amounts　of　V2O5　could　be　improved　under　the　same　experimental　conditions　for　acidity　enhancement.