Mercury emission from coal combustion has been the fourth biggest pollutant in China, following the dusts, SO2 and NOX. The technology of non-thermal plasma has been widely studied for oxidizing gaseous elemental mercury at low temperature. In this paper, a new method of combining non-thermal plasma with calcium oxide was proposed to remove elemental mercury from simulated flue gas. The effects of non-thermal plasma, input energy, combination mode of plasma and calcium oxide on Hg-0 removal were investigated in a wire-cylinder non-thermal plasma reactor, whose energy was supplied by a high voltage alternating current power. The peak voltage and energy of the non-thermal plasma were measured by an oscilloscope and a high voltage probe (1000:1). The results showed that most of Hg-0 was converted to oxidized mercury in simulated flue gas by non-thermal plasma treatment. The Hg-0 removal efficiency of CaO was improved remarkably strengthened by the non-thermal plasma, which was closely related to input energy, and the maximum mercury removal efficiency was about 80 % at an optimal input energy. Through temperature-programmed decomposition and desorption and energy dispersive spectroscopy analysis, the majority of mercury species on CaO surface were Hg2O and HgO3 rather than HgO. Therefore, it can be concluded that O-3 plays an important role in Hg-0 oxidation under the condition of non-thermal plasma.