The work aims to study the effect of glyceride triacetate (GTA) on the properties of PLA/PHB packaging film. By adding GTA, the compatibility of PLA with PHB, and the water vapor permeability and oxygen permeability of the packaging film were improved. PLA/PHB composite film were prepared by melt blending for film blowing with GTA as plasticizer, and polylactic acid (PLA) and poly (3-hydroxybutyrate) (PHB) as raw materials. The effects of different GTA mass fractions on the tensile property, elongation at break, water vapor permeability and oxygen permeability and compatibility of the composites through the DSC test of the composites and analysis on the water vapor permeability and oxygen permeability, mechanical property and infrared spectroscopy were studied. With the GTA content increased, the tensile strength of the film decreased integrally, but the elongation at break showed a tendency to increase. When the mass fraction of GTA was more than 4%, the tensile strength decreased sharply, and the elongation at break increased rapidly first and then slowly. The water vapor permeability increased firstly and then decreased with the increase of GTA mass fraction, and the oxygen permeability showed no significant increase. By observing the DSC diagram and the microgram of the packaging film section, it was found that the addition of GTA weakened the force acted between the polymer molecular chain segments and promoted the movement of chain segments, making the pores of the film cross section disappeared to form a layered structure. The addition of GTA improves the compatibility of PLA and PHB. When the mass fraction of GTA was 4%, the composite packaging film has better tensile property and elongation at break with better water vapor permeability and oxygen permeability.