Catalytic performances of copper complexes, which consisted of Cu(OAc)2 as a copper source and 2,2'-biimidazole (H2biim), 1,1′-dimethylene-2,2′-Biimidazole (DMe-H2biim) or l,l'-ο-Xylylene-2,2'-biimidazole (Oxy-H2biim) as a ligand, were investigated in oxidative carbonylation of methanol to dimethyl carbonate (DMC), and Cu(DMe-H2biim)(OAc)2 was characterized by infrared spectroscopy, thermogravimetric analysis and CO temperature-programmed reduction. It was found that DMe-H2biim exhibited the higher performance for DMC synthesis than H2biim and Oxy-H2biim due to the electron-donating effect of the methylene group, and the catalytic activity of Cu(DMe-H2biim)(OAc)2 was higher than that of the equimolar mixture of Cu(OAc)2 and DMe-H2biim. The turnover number and the selectivity of DMC reached 20.4 molDMC/molCu and 95.8% under the conditions of Cu(DMe-H2biim)(OAc)2 as the catalyst, reaction time 4 h, reaction temperature 110 癈 and the concentration of the catalyst 0.011 mol/L.