Poly (lactic acid) (PLA) blended with poly (butylene succinate) (PBS) were prepared by using twin screw extruder and injection molding machine at various contents of PBS from 0-15 wt%. The surface of titanium dioxide (TiO2) nanoparticles was treated using aminopropyl trimethoxy silane (ATS) order to disperse them into the biopolymer blends. The mechanical and thermal properties of PLA/PBS/TiO2 nanocomposites were investigated over a range of filler content 0-5 wt%. All samples with a wide range of TiO2 addition exhibit the translucency. The surface morphology showed that the addition of PBS at 10 wt% was miscible with PLA while the other contents of PBS exhibited phase separation in the blends. Additionally, a uniform dispersion of filler in the matrix existed when the nanoparticles content was less than 3 wt%. The surface treated nanoparticles played an important role in mechanical and thermal properties of the nanocomposites because of its well dispersion and strong interfacial interaction between the nanoparticles and PLA/PBS matrix.