The hot air seam sealing machine is used to attach adhesive tape to a sewing area, using a high temperature, in order to achieve an excellent waterproof performance. The sealing machine is applicable for seamless welding of raincoats, windbreakers, ski clothing, screens, tents, military waterproof covers, waterproof bags, portable car covers, PVC fabrics made of nylon-PVC, nylon-PU, rubber cloth, three-layer cloth and other fabrics with waterproof coatings. It is also an ideal replacement for high frequency welding machines.