This article deals with the definition, classification and testing of barrier property of materials. Common erroneous views and vague knowledge are also listed in each item with corresponding rectification.

With the popularization of the conception of barrier property, insiders of the packaging industry have the demand to further the understanding of barrier property. A further understanding of barrier property will not only help packing manufacturers design the structure of packing materials effectively and reasonably, but help the research personnel to better their performance of relating test as well.