Poly (lactic acid) (PLA) is biodegradable and compostable polymer with great potential for substitution of non-biodegradable polymers, particularly those that are applied in products with quick shelf live. PLA fulfils the packaging industry’s requirements for most of the rigid objects but the polymer needs to be plasticized to be used as soft films. In this paper, the aim was evaluate the effect of plasticizer and graphene dispersion in PLA properties. The plasticizers used were polyethylene glycol (PEG) and dibutyl sebacate (DBS). Plasticizers have been used as diluents in graphene nanoplatelets pre-dispersion via sonication and then this mixture was added in melted PLA. Thermal properties were evaluated by differential scanning calorimetry and thermogravimetric analysis and water vapor permeability test were carried out by ASTM method E96. The DBS addition decreased glass transition temperature (Tg) and PLA water vapor permeability in approximately 50%. It is also observed PEG addition decreased thermal stability and accelerates PLA water degradation. The graphene nanoplatelets addition improve water vapor barrier properties up to 40%. Besides, an increase in crystallinity degree was also observed with graphene addition.