A multi-purpose air-packing method and system enables to pack a product having an irregular shape easily at low cost. The air-packing method includes the steps of placing a product to be protected in a container box; applying a first air-packing device having a plurality of air containers to side surfaces of the product in a manner to surround the product in the container box where each of the air containers has a check valve to maintain compressed air therein independently from one another; and inflating the air-packing device by supplying compressed air to securely hold the product within the container box. Two or more consecutive air containers at one end of the first air-packing device have a cross sectional size smaller than that of other air containers.