The work aims to study the thermal, mechanical properties and gas permeability of uniaxial drawn poly(l-lactic acid)/poly(butylene adipate-co-terephthalate) (PLLA/PBAT) blending film. The uniaxial drawn PLLA/ PBAT blending films with different PBAT contents were prepared via a twin screw extruder, and the thermal, mechanical properties and gas permeability thereof were studied. PLLA and PBAT were totally incompatible blending systems. The addition of PBAT accelerated the cold crystallization rate of PLLA and improved the flexibility of uniaxial drawn PLLA film in the vertical and horizontal directions, with the maximum elongation at break of 29%. The gas permeability and permselectivity of CO2/O2 were improved. Compared to the transmittance (3.8) of pure PLLA, the transmittance of CO2/O2 was improved to 7.6. The addition of PBAT improves the rigidity of neat PLLA and enhances the flexibility of materials. Due to good adsorbability and diffusivity of PBAT for CO2, the CO2 permeability and the permselectivity of CO2/O2 of the material are well improved.