The potential of the sorbent-catalysts prepared from three low cost materials, i.e., the lime, fly ash and some industrial waste material containing iron oxide, have been investigated for simultaneous removal of SO2 and NOx from flue gas in the temperature range 700-850 ℃. NH3 was chosen as the reducing agent for NO reduction in this study. Experimental results showed that SO2 and NO could be simultaneously removed efficiently in the absence of O2 at the temperature window of 700-800 ℃. The effect of product layer generated from SO2 removal on NO removal was not obvious. NO removal efficiency was strongly inhibited by O2, which was attributed to the partial oxidation of NH3 to NO over the sorbent-catalysts in the presence of oxygen. Neither NO2 nor N2O by-product was detected both in the absence and presence of O2. Three routes were suggested to overcome the negative effect of O2.