Vinylene carbonate was synthesized using vinyl chloride carbonate and sodium bicarbonate as raw materials by a molecular sieve circulating dehydration process. After optimizing the synthesis process conditions, the purity of vinylene carbonate reached up about 96% by the analysis method of gas chromatography，and its purity yield is 81.24%. Compared with traditional processes, this synthesis process has no by-products of triethylamine hydrochloride, no need for pressure filtration, and less solvent usage; The byproducts CO2, NaCl, and H2O can be removed through venting, sedimentation, and molecular sieve adsorption, respectively. Moreover, the external circulation adsorption dehydration process is not limited by the solvent boiling point, has fewer components in the crude reaction solution, high yield, easy separation, and low energy consumption.