【Objective】 Organic Se is an important component of total Se in soil, and selenomethionine exists as one of the most common species among the organic Se. Given that the interfacial interaction between iron oxides in soil and organic Se species remains elusive, this study provides an avenue for understanding the migration and transformation of Se coupling with Fe-cycling in soil. 【Method】 In this study, the interfacial interaction between selenomethionine and iron oxides, ferrihydrite, goethite, and hematite was investigated through the analysis of surface species, coordination structure of iron atom (Fe) and adsorption configuration over the X-ray photoelectron spectrum (XPS), X-ray absorption fine structure spectrum (XAFS), and attenuated diffuse reflection infrared spectrum (DRIFTS-IR). 【Result】 The results revealed that the binding energy (B.E.) of N1s was decreased to 399.7 eV and it was maintained for the main Se species adsorbed on ferrihydrite. The coordination structure of first- and second-sphere for Fe atom of ferrihydrite before and after interacting with selenomethionine did not change, while there was an adsorbed carboxyl-species with bidentate coordination mode. This result suggested that selenomethionine could be adsorbed on ferrihydrite through the bidentate coordination mode with a vertical adsorption configuration over carboxyl on the surface of ferrihydrite. After interacting with selenomethionine, the B.E. of Fe for bulk FeO₆ at the goethite sub-surface was reduced by 0.4 eV. Also, the distance of first-sphere and coordination number of outer spheres for Fe atom in goethite showed an obvious change, compared to that of the fresh goethite. It indicated that goethite had undergone an obvious dissolution accompanied by obvious reduction effect after interacting with selenomethionine. Moreover, the Se atom mainly existed as the oxidized species on goethite. There was a monodentate coordination mode for the adsorbed selenomethionine on goethite with a horizontal adsorption configuration. For hematite, the B.E. of Fe both at sub-surface and surface were reduced to 0.4 eV, while the coordination structure of Fe atom for the Fe-sphere did not change but shortened in the first-sphere. This phenomenon revealed a characteristic weak dissolution interaction and a strong reducibility for hematite interacted with selenomethionine. Owing to the reduction by selenomethionine, there was a strong surface-enhanced infrared absorption effect for the adsorbed selenomethionine. Besides, the amino N and Se atoms might directly participate in the chemical adsorption of selenomethionine on hematite. Among the three iron oxides, there was a similar oxidization pattern for Se during the interaction process and this observation can be summarized as: 1) the complete oxidization of selenomethionine into selenite and 2) the incomplete oxidization species of selenomethionine. 【Conclusion】 The interaction characteristic and mechanism of selenomethionine with ferrihydrite, goethite, and hematite was carefully revealed through surface analysis. The results revealed a differential response for the surface structure of mineral and change of selenomethionine when it interacted with iron oxides with different surface structure and properties. These findings provide an important reference for understanding the migration and transformation of organic Se in soil under different Fe-cycling processes. It also provides guidance for the utilization of Se resource and remediation of Se pollution in Se-rich areas.