Abstract: Traditional Ce-Cu catalysts are known for their effective low-temperature decarbonization activity but are susceptible to performance degradation in the presence of SO₂ in flue gas. In this study, the impact of Fe-Sm doping on the decarbonization efficiency and resistance to SO₂ of Ce-Cu catalysts was investigated. Through the application of the co-precipitation method to introduce Fe-Sm and utilizing characterization techniques including XRD, SEM, N₂ adsorption-desorption, TEM, and XPS, the mechanism of Fe-Sm doping on the catalyst was elucidated. Results demonstrated that with a Ce:Cu:Fe:Sm ratio of 10:3:2:3, the catalyst maintained stable decarbonization performance at 250℃ and a space velocity of 60000 mL·g⁻¹·h⁻¹ under simultaneous exposure to 1% CO, 10% H₂O, and 0.01% SO₂. After 3 hours of stable reaction, the decarbonization efficiency began to decline, with the conversion rate decreasing from 100% to 70% after 4.2 hours. In comparison, the Ce-Cu catalyst exhibited stability for only 2 hours under the same conditions, highlighting the enhanced sulfur resistance conferred by Fe-Sm incorporation. Characterization analysis revealed the formation of a solid solution of Fe-Sm with Ce-Cu, uniformly dispersed on the catalyst surface. The 10Ce-3Cu-2Fe-3Sm catalyst displayed improved particle uniformity, increased surface porosity, higher specific surface area, and pore volume. The addition of Fe-Sm resulted in elevated Ce³⁺ and Cu⁺ concentrations, surface oxygen atom concentration, and O_α. These are more conducive to the catalytic oxidation of CO in SO₂ atmospheres. Overall, the 10Ce-3Cu-2Fe-3Sm catalyst exhibited superior sulfur resistance, providing a theoretical basis for the application of non-precious metal oxide decarbonization catalysts in sulfur-containing environments.