Abstract: In order to improve the catalytic oxidation activity of the commercial selective catalytic reduction (SCR) catalyst for removal of Hg⁰ in flue gas, a transition metal oxides doped SCR catalyst by impregnation method was employed to improve the Hg⁰ catalytic oxidation. Moreover, the fixed bed reaction platform was used to investigate the modified catalyst under different test conditions for Hg⁰ catalytic oxidation efficiency. Hg⁰ catalytic oxidation efficiencies of the modified catalysts by transition metals were tested in a pack-bed reactor system under different experimental conditions. The results showed that the catalytic performance of the SCR catalyst was remarkably inhibited by Y, Zn, Ni and Zr, and greatly enhanced by Fe and Cu. The Hg⁰ oxidation efficiency of the SCR doped with Fe or Cu was over 90% when the reaction temperature, space velocity and HCl concentration were set as 350 ℃, 370,0 h-1 and 1×10-5, respectively. Furthermore, Fe doping the catalyst did not obviously affect the NO_x removal efficiency of the SCR catalyst. In addition, XRD and XPS were employed to characterize the SCR catalyst doped with Fe. The results indicated that the SCR catalyst doped with Fe showed good performance of Hg⁰ oxidation according to the Mars-Maessen and Langmuir-Hinshelwood mechanisms. Therefore, SCR modified with Fe has good application prospects for the simultaneous removal of elemental mercury and NO_x.