The present invention provides a method for preparing a cyclic carbonate, which has the advantages of high yield, mild reaction conditions, high catalytic efficiency under room temperature and 1 atm pressure conditions, and wide substrate scopes. It is not only suitable for monosubstituted epoxides, but also suitable for disubstituted epoxides. The method comprises the step of reacting epoxides of Formula (I) with carbon dioxide in the presence of a quaternary ammonium salt and a catalyst, to obtain a cyclic carbonate of Formula (II). The reaction formula is: