Method for preparing highly transparent and highly heat-resistant polycarbonate ester

The present invention relates to a method for preparing a bio-based polycarbonate ester, the method comprising the steps of: (1) preparing a compound represented by chemical formula 3 by converting a compound represented by chemical formula 2 into an intermediate reactant having an easily detachable functional group, followed by a nucleophilic reaction with phenol; and (2) preparing a compound including a repeat unit represented by chemical formula 1 by a polycarbonate melt condensation polymerization of the compound represented by chemical formula 3, prepared in step (1), a compound represented by chemical formula 4, and 1,4:3,6-dianhydrohexitol. The bio-based polycarbonate ester according to the present invention can regulate merits and demerits of physical properties obtained from each repeat unit, and can be favorably used for various uses due to high degrees of transparency and heat resistance thereof.