The work aims to improve the barrier properties of PBAT film, prepare coating film with glutaric acid as a crosslinking agent modified PVA and prepare PBAT/PVA composite film with high barrier properties by coating method. Infrared spectroscopy, differential scanning calorimeter, contact angle tester, water vapor transmission rate tester, etc. were used to study the structure and performance of modified PVA mono film and PBAT/PVA composite film. The results showed that glutaric acid had a certain esterification effect with PVA, which consumed part of the hydroxyl groups in PVA, thereby improving the water resistance of PVA. Glutaric acid modification improved the hydrophobicity of the PVA film, and its contact angle increased from 11.3° to 60.6°. Compared with the pure PBAT film, the water vapor transmission rate of the composite film modified by glutaric acid for 3 h was reduced from 647.95 g/(m2.24 h) to 132.07 g/(m2.24 h), and the oxygen transmission rate was reduced from 17 730.3 cm3/(m2.d.MPa) to 396.6 cm3/(m2.d.MPa), which proved that the PVA coating liquid modified for 3 h was most helpful to increase the PBAT barrier properties. The PBAT/PVA composite film prepared by coating method has high barrier property, which lays a foundation for the wide application of PBAT.