In this study, the effect of nano-particles on the properties of plasticized and improved flame retardancy with triphenyl phosphate (TPP) of poly (lactic acid) PLA were investigated. Plasticized PLA/TPP was used as control sample. Different amounts of carbon nanotubes (CNT), nanoclays (NC) and aminopropyl isobutyl poly (hedral oligomeric silsesquioxane) (A-POSS) particles were added to this composite due to decreasing TPP amount. Nanocomposites were prepared by using extruder and injection molding equipment. The characteristic properties of composites were determined by using mechanical, thermal, and morphological and flammability tests. 1% A-POSS containing nanocomposite were showed highest breaking strength and elongation at break value. The breaking strength and elongation value decreased due to the increasing loading level of nanoparticles. The decomposition temperature of A-POSS and all prepared composites is higher than the processing temperature. Scanning Electron Microscope (SEM) analysis for TPP, NC and CNT containing nanocomposites exhibited the more homogeneous filler distribution. While the Transmission Electron Microscope (TEM) analysis supported this result, nano scale aggregation is observed for the A-POSS containing nanocomposites. Highest Limiting Oxygen Index (LOI) value was obtained for the NC including composites. 1 and 2 % NC including composites were showed V-0 class according to the UL-94 flammability test.