In this research, PLA/PEG blends containing 5, 10 and 15 w.% of PEG and also Nanocomposite of PLA/PEG (85/15 wt./wt.) with 0.05, 0.15 and .75 phr Nano Ag were prepared via melt mixing using an internal mixer. The mechanical and thermal properties of blends and nanocompositses, also their morphology were studied. DSC and DMTA results illustrated one Tg for PLA/PEG blends, which shows their miscibility in all studied compositions. Also the Tg and Tm of blends were decreased by increasing the PEG contents. The tensile and impact tests showed that the modulus and tensile strength of blends are decreased and their elongation at break and impact strength are increased by increasing the amount of PEG. In contrast, the addition of nano Ag to PLA/PEG 85/15 blend, led to increasing the tensile strength and modulus and decreasing the elongation at break and impact strength. Using EDAX, it was found that nano Ag particles are well dispersed in the nanocomposite samples. TGA showed that destruction temperature of composites are increased by increasing the amount of nano particles. Finally, the antimicrobial tests on nanocomposite sample containing 0.75 nano Ag, showed that it is sensitive to both gram-positive and gram- negative bacteria, but its antimicrobial property is more powerful in contact with gram- positive ones. Keywords: Poly(lactic acid), Poly (Ethylene glycol), Nano Ag, Antimicrobial, nanocomposites