Disclosed is a method for preparing a poly(L-lactic acid) composite. According to the method, PLLA can be processed without losing its physical properties during thermal processing and can be effectively used to manufacture a final product with improved thermal properties. In addition, the monomer is not thermally decomposed during high-temperature polymerization. Therefore, the poly(L-lactic acid) composite can be prevented from browning. Also disclosed is a poly(L-lactic acid) composite prepared by the method.