Direct synthesis of dimethyl carbonate from CO, and methanol was investigated at near supercritical conditions using nickel acetate as the catalyst. It was demonstrated that dimethyl carbonate could be produced as the unique product at such low temperature as 305 K and the yield was 12 times higher than that at non-supercritical conditions. The synthesis was sensitive to the reaction pressure and showed a maximum for DMC yield at the ressure of 9.3 MPa. The concentration of methanol showed an obvious influence on both the yield and selectivity of DMC. Nickel acetate appeared to be the precursor of the catalyst. The formation mechanism of dimethyl carbonate in supercritical phase was proposed.