Selenization of Fe2O3 with NaHSe led to Se/Fe3O4. The unexpected generation of Fe3O4 attributed to the reduction conditions of the reaction, and the resulted magnetic features of the material facilitated its separation in practical applications. Owning to the synergistic effect of Se with Fe, the material was especially active to catalyze the oxidative C=C scission using O2 as mild oxidant. The technique has been successfully applied in polyene degradation project, which is of profound practical values for the treatment of the polyene pigment pollution and may be applied in the food and pharmaceutical industry.