Abstract-The present research reports the investigation of the role of an oligomeric polyadipate plasticizer (206 3NL), and a nucleating agent aromatic sulfonate derivative (LAK301) on thermal behaviours of poly-lactic acid (PLA) evaluated through differential scanning calorimetry (DSC) measurements in order to investigate the separated effect due to the addition of plasticizer and nucleating agent on the thermal behavior of PLA respectively. Binary and ternary systems containing PLA/206 3NL/LAK301 have been developed. All samples have been prepared by melt-blending. The results of the present study show that LAK301 acts as a very efficient nucleating agent by increasing crystallinity percentage from 5.6% in pure PLA to 12% in PLA/LAK301 5%wt/206 3NL, and that (206 3NL) is a compatible plasticizer for PLA as the glass temperature drops down from 59.4 °C in pure PLA to 38.9 °C in blends of PLA-NL 15 wt%. Also the approach of investigating the compatibility in ternary system where the plasticizer and nucleating agent have a synergic effect on thermal properties as well on crystallinity and glass transition temperature of PLA were addressed. In fact in ternary blends of PLA/LAK301/206 3NL with 5 wt% of LAK301 the glass transition temperature was reduced to 30.3 °C and PLA crystallinity increased to 39 wt%.