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• Synergistic interaction of Sm and Fe enhanced Pb-resistance of Mn-Ce/AC catalyst. • Sm and Fe co-doping alleviated the damage of Pb species to catalyst structure. • Surface acidity and redox ability of Mn-Ce/AC catalyst were protected by Sm and Fe from lead. • NH 3 -SCR reaction on catalysts after Pb poisoning followed L-H and E-R mechanism. A novel anti-Pb poisoning Sm and Fe co-doped Mn-Ce/AC catalyst was prepared by impregnation method for low-temperature NH 3 -SCR of NO reaction. Maintaining the excellent low-temperature activity of Mn-Ce/AC catalyst, Sm and Fe co-doping remarkably enhanced the catalyst's Pb-resistance with NO conversion up to 77%. Sm and Fe co-doped poisoning-catalysts exhibited large specific surface area and pore volume, and the crystallinity of the MnO x and CeO x reduced. The redox properties and surface acidity of the lead poisoned SmFeMnCe/AC catalyst were effectively retained, which could promote NO oxidation and NH 3 activation, further benefiting the SCR reaction. In situ DRTFTS results indicated that the low-temperature NH 3 -SCR mechanism of all poisoned catalysts followed both L-H mechanism and E-R mechanism, and the L-H mechanism was dominated. On the one hand, the extraordinary lead resistance of Sm weakened the damage of lead species on the physicochemical properties of the catalyst; on the other hand, the high oxidation properties and surface acidity of Fe enhanced the catalytic activity of the poisoned catalyst. Finally, a possible synergistic mechanism model of Sm and Fe co-doping on Mn-Ce/AC catalyst against Pb-poisoning was proposed. [ABSTRACT FROM AUTHOR]