Converting of elemental mercury (Hg-0) into oxidized mercury compounds is considered to be an effective method for prompting mercury removal of conventional flue gas treatment systems. The technology of non-thermal plasma (NTP) with CaCl2 treatment was utilized to oxidize Hg-0 in this paper. The effects of input energy and different flue gas components like O-2, NO and SO2 on Hg-0 oxidation were investigated. The results showed that the Hg-0 oxidation efficiency with CaCl2 treatment was increased obviously compare with single NTP treatment, and would be more than 90% when the input energy was 120 J/L. The O-2 in simulated flue gas played an important role for mercury oxidation. The Hg-0 oxidation efficiency and O-3 outlet concentration were increased with the increase of O-2 content. However, both NO and SO2 inhibited Hg-0 oxidation due to their competitive consumption of O-3 and O. Compare with single NTP technology, the effects of NO and SO2 on Hg-0 oxidation under NTP with CaCl2 treatment were decreased obviously. The technology of Temperature-Programmed Decomposition and Desorption was utilized to analyze the mercury speciation adsorbed or deposited on AC and CaCl2 surface. The results concluded that the main Hg-0 oxidation products by NTP with CaCl2 treatment were HgO, Hg2O and HgCl2, which indicated that the chlorine of CaCl2 surface was the main reason for enhancement of Hg-0 oxidation.