A vapor phase synthesis of diethyl carbonate (DEC) from carbon monoxide and ethyl nitrite (EN) was studied in a continuous flow micro fixed-bed reactor at atmospheric pressure. PdCl2-CuCl2/AC (activated carbon) catalyst exhibited better catalytic activity compared with other binary catalyst systems. The suitable Pd-loading is about 2.0 wt%, and some additives (LaCl3, CeCl3, PrCl3) are benefit for the DEC yield and selectivity. Influences of various reaction parameters on the DEC yield and selectivity were tested. The optimum reaction temperature lies in 378-388K and the suitable gas hourly space velocity (GHSV) range is 2500-3000 h-1 considering both factors of DEC production and CO conversion. An optimum CO/C2H5ONO mole ratio exists for catalytic activity, which is about 1/1. The stability of PdCl2-CuCl2/AC catalyst and PdCl2-CuCl2-CeCl3/AC catalyst was also investigated. The possible reason of the deactivation behavior of catalysts was discussed with the help of XRD.