As for the issue of low efficiency in desulfurization with conventional activated carbon，in the study of this paper the iron-based activated carbon (Fe_x/AC) was prepared via impregnation modification of ferric nitrate to systematically study the enhancing effect and mechanism of the iron element on the desulfurization performance of activated carbon. The results show that iron modification improved the adsorption performance of the activated carbon.When the iron loading was 15%，the breakthrough time of Fe_0.15/AC in a fixed-bed reactor reached 296 min，which was 3.7 times longer than that of the unmodified activated carbon (80 min).Moreover，it maintained 100% desulfurization efficiency even under high space velocity (3 000 h^-1 ) conditions in a moving bed.Characterization analysis results indicate that an appropriate amount of iron loading not only can improve the proportion of surface functional groups but also can regulate the pore structure，making the distribution of micropores and mesopores more conducive to the diffusion and reaction of SO₂. Further in-situ FTIR and XPS analysis revealed that iron oxides( Fe³⁺/Fe²⁺ ) can form Fe—O—C coordination structures with carbonyl(C=O) groups，promoting the chemisorption and deep oxidation of SO₂ through redox cycling. Additionally， in-situ FTIＲtest results verified the gradual formation process of sulfate. Overall，the stable reactive sites constructed by the iron element on the activated carbon surface，coupled with its reversible redox properties，jointly promote the enhancement of desulfurization performance.The findings of this study can provide references for optimizing iron loading，improving pore structure，and enhancing the desulfurization capacity of activated carbon.