The invention discloses a method for synthesizing diethyl carbonate and coproducing diol by using carbon dioxide, belonging to the field of synthesis of organic chemicals. An epoxy compound, the carbon dioxide and ethanol are used as raw materials and directly esterified in the presence of a catalyst to prepare the diethyl carbonate, and the diol is also coproduced; and the catalyst is characterized by consisting of an alkali metal halide and an alkali catalyst which are used as active ingredients, wherein the weight ratio of the epoxy compound to the catalyst is 100: (1-5), the reaction temperature is 80-230 DEG C, the reaction pressure is 0.5-15MPa, and the reaction time is 0.01-5h. The diethyl carbonate is synthesized by directly using the CO2, the epoxy compound and the ethanol, so the yield and selectivity of the target product are relatively high, the production cost of the diethyl carbonate can be reduced, and the diethyl carbonate has good industrial application value.