Abstract: A aseries of Co-doped BiFeO₃ magnetic catalysts(BiFe_1-xCo_xO₃, x=5%-20%) were synthesized by the tartaric acid sol-gel method, and the prepared catalysts were characterized using X-ray powder diffraction (XRD), Brunauer Emmett Teller (BET) technique, vibration sample magnetometer (VSM) and X ray photoelectron spectroscopy(XPS). The catalytic activity of Co doped BiFeO₃ to activate Peroxymonosulfate (PMS) was evaluated at a self-designed bubbling reactor. The effects of Co ration in catalyst, dosage of the catalyst, PMS concentration, and solution pH and reaction temperature on the removal of elemental mercury were investigated systematically, and the optimum conditions were obtained. The result indicates that the average removal efficiency of elemental mercury reaches 89.36% within 100 min under the following condition:70℃, 10% doping Co, 3.9 mmol/L PMS concentration, 0.5 g/L catalyst dosage and pH 8. Moreover, it is testified that SO₄^·- and·OH are the active species when Hg⁰ is oxidized to Hg²⁺, where the tert-butyl alcohol and ethyl alcohol are used as quenchers. Finally, the mechanisms of mercury removal with PMS solution catalyzed by BiFe_0.9Co_0.1O₃ are speculated on the basis of XPS results.