The blends of PLA/Starch containing Epoxidized Soybean Oil (ESO) as a compatibilizer, were made using an internal mixer, while the compositions of Starch and ESO were kept at 12.5 wt.%. Then 1, 4 and 7 wt.% of Nano Calcium Carbonate (NCC) were added to the mentioned blend respectively. The mechanical and thermal properties, as well as crystallinity, morphology and foamability of neat PLA, its blend with starch and nanocomposites were studied. It was found that ESO is a good compatibilizer for PLA/Starch blend and the elongation at break, also the impact strength of neat blend and nanocomposites are improved by using ESO. Also the results showed that using NCC leads to improvement in mechanical properties like tensile strength and modulus of the samples. In the other hand, NCC can play the role of nucleating agent and increase the crystallinity of PLA. Finally the neat blend and nanocomposites were foamed in an autoclave using high pressure Nitrogen gas. It was shown that the PLA/Starch/ESO/NCC foams have smaller cell size and higher cell density in comparison with neat blend. This is due to NCC, which acts as a nucleating agent for foaming process. So the heterogeneous nucleation via NCC, is happened and the homogeneous morphology and cell size are achieved. Also it was found that the cell density in nanocomposite samples is much smaller than neat blend. For example, in nanocomosite foam sample containing 4 wt.% NCC, the average cell size is decreased from 115 to 30 ìm.