In this paper, the heterogeneous reactions of H₂O₂ and SO₂ on the surface of mineral oxides (α-Fe₂O₃) were simulated by density functional theory. The adsorption mechanism and oxidation mechanism of H₂O₂ and SO₂ on the surface of α-Fe₂O₃ (001) were studied. The results showed that both SO₂ and H₂O₂ were adsorbed by Fe atoms on the surface of α-Fe₂O₃ (001). Compared with SO₂, H₂O₂ adsorbs preferentially on the surface of α-Fe₂O₃ (001), and the forms of H₂O₂ on the surface tend to be two ·OH forms. Through the analysis of the local density of states, differential charge density and Mulliken charge distribution, it was found that the co-adsorption of SO₂ and H₂O₂ was in the form of ·OH generated by H₂O₂ adsorbed on the surface of α-Fe₂O₃ (001), while SO₂ was oxidized by ·OH[S_(SO2) -charge distribution:0.79 e→1.32 e; O_(H2O2)-charge distribution:-0.77 e→-1.11 e], and ·OH+SO₂ clusters were formed. These data show that the atmospheric trace gas H₂O₂ can mediate the adsorption of SO₂ on the surface of mineral oxides and promote the transformation of SO₂. The results obtained by the authors provide a theoretical basis for understanding the heterogeneous oxidation of SO₂ by trace H₂O₂ in the atmosphere.