The Cu-x-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) bimetal oxides catalysts were synthesized through citric acid method and used in the selective catalytic reduction (SCR) of NO with NH3. The relationship among the catalytic performances, the acid/redox properties and the structures of the binary oxides systems was explored through different characterization techniques including XRD, H-2-TPR, BET, NO-TPD, NH3-TPD, XPS and in situ DRIFTS. The characterization results point out that the ratio of Cu to Nb has great influence on the activity of NH3-SCR reaction. Different catalytic activities of Cu-x-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) mixed oxides could be attributed mainly to surface area, acid amount, the adsorption and activation of NH3 and redox ability of the corresponding catalyst. Among these Cu-x-Nb1.1-x (x = 0.45, 0.35, 0.25, 0.15) oxides catalysts, the Cu-0.23-Nb-0.83 catalyst exhibited the complete NO conversion in a reaction temperature range of 180-330 degrees C, together with near 100% N-2 selectivity and remarkable SO2/H2O resistance. Moreover, the Cu-0.23-Nb-0.83 catalyst still exhibited wide activity temperature window of 185-380 C at above 90% NO conversion even in the presence of 5% H2O under high GHSV of 70,000 h(-1). Thus, it can be summarized from the above results that Cu-0.23-Nb-0.83 can be considered as excellent catalyst for NH3-SCR of NO.