The strength of intermetallic interaction could directly affect many properties of catalysts. In this study, it was found that the modification of Mn/TiO2 catalyst by Fe could enhance the SO2 tolerance, but had little effect on SCR activity. The doping of Cu had an improvement in both the SCR activity and SO2 tolerance of the catalyst. XRD, Raman, TGA-IR, XPS, H-2-TPR, NH3-TPD, and BET were carried out to dissect the structures and properties of catalysts. The interaction between Fe or Cu and Mn resulted in some adverse effects on the acidity, Mn4+ and surface chemisorbed oxygen concentration. However, the reduction ability of Mn/TiO2 catalyst decreased after Fe doping, while Cu doping was just the opposite. In addition, the interaction between Cu and Mn was stronger, and a new CuMn2O4 phase was formed. What's more, the interaction between Fe or Cu and Mn could weaken the sulfation of Mn and the formation of ammonium salts in the environment of sulfur dioxide. [GRAPHICS] .