The invention discloses a reinforcing structure of an inflatable product. The reinforcing structure comprises an upper sheet, a lower sheet, a plurality of drawstrings and an enclosing sheet, wherein two ends of each drawstring are respectively connected to the lower surface of the upper sheet and the upper surface of the lower sheet, and meanwhile, the upper edge and the lower edge of the enclosing sheet are respectively connected with the circumferential edge of the upper sheet and the circumferential edge of the lower sheet to form an inflatable product with an inflatable space; and the reinforcing structure further comprises a side enclosing drawstring, wherein one end of the side enclosing drawstring is connected to the middle part of the inner surface of the enclosing sheet, the other end of the side enclosing drawstring is connected to the lower surface, close to the circumferential edge, of the upper sheet and the upper surface, close to the circumferential edge, of the lower sheet, or the other end of the side enclosing drawstring is connected to the opposite surface of the enclosing edge connected with the one end of the side enclosing drawstring. According to the reinforcing structure, the side enclosing drawstring can have a certain traction limiting effect on the middle part of the enclosing sheet of the inflatable product with high height so as to prevent the inflatable product from protruding outwards too much to influence the strength and attractive appearance of the inflatable product, therefore not only is the material cost of the inflatable product effectively reduced, but also the manufacturing cost of the inflatable product can be effectively reduced.