The invention discloses a method for preparing cyclic carbonate. The method specifically comprises the following step: with a quadri-aryloxy bridged rare earth metal compound as a catalyst, catalyzing carbon dioxide and alkylene oxide to react in the present of quaternary ammonium salt, wherein the general formula of the quadriaryloxy bridged rare earth metal compound is LLn(THF), wherein L refers to ethanediamine group bridged quadri-aryloxy, Ln refers to rare earth metal ions, and the quaternary ammonium salt is one of tetrabutylammonium iodide, tetrabutylammonium bromide, tetrabutylammonium chloride, tetraoctyl ammonium bromide, bis(triphenylphosphine) ammonium chloride and benzyl butyl ammonium bromide. The rare earth catalyst in the catalysis system is clear in structure, easy to synthesize, high in catalysis activity, less in using amount, mild in reaction conditions and wide in universality to alkylene oxide. According to the preparation method disclosed by the invention, raw materials are easily available, the reaction conditions are wild, a reaction substrate is wide in universality, the reaction time is short, the yield of the target product, namely the cyclic carbonate is high, and the reaction operation and the posttreatment process are simple.