The work aims to study the change of oxygen and water vapor permeability amount of plastic film for food packaging with different thicknesses and materials, so as to provide basis and guidance for food packaging in the material selection regarding the barrier property. The amounts of oxygen and water vapor permeability of plastic film were respectively measured in the pressure difference method and cup method. With the increase of the thickness, the amount of oxygen and water vapor permeability of the single layer plastic film decreased, and the barrier property became better. Among such four single layer plastic films as PE, PET, BOPP and PA of the same thickness, the oxygen permeability amount of PA was the lowest and PE's was the highest; and the water vapor permeability amount of BOPP was the lowest and PA's was the highest. With the increase of composite film thickness, both its oxygen permeability amount and water vapor permeability amount decreased, but the decrease gradually became smaller. When the thickness of the outer material of the plastic-plastic composite film remained unchanged, the oxygen and water vapor permeability amount always changed little with the total thickness. The oxygen and water vapor permeability amount of the EVOH plastic composite film was relatively low, generally less than 5. The oxygen and water vapor permeability amount of the aluminum foil plastic composite film was less than 1. Among the single layer plastic films, PA has the best oxygen barrier property and PE has the worst one; BOPP has the best barrier property of water vapor and PA has the worst one. Among the composite films, the barrier property of the plastic-plastic composite film mainly depends on the outer material. The aluminum-plastic composite film has the best barrier property. The barrier property of plastic composite film containing high barrier material EVOH is better than that of the ordinary plastic-plastic composite film and its barrier property can be comparable to that of the aluminum-plastic composite film.