The present invention relates to a polypropylene-polylactic acid composite composition comprising a mixture of polypropylene resin and polylactic acid resin, wherein ethylene-octene copolymer grafted by anhyrdrous maleic acid, polylactic acid resin grafted by anhydrous maleic acid, polyethylene-glycidyl methacrylate resin and talc particles are added thereto. The composition reduces CO2 emission and improve mechanical strength and heat resistance, thereby being suitable as a material for the interior and exterior parts of a vehicle as well as construction.