An inflatable decorative system includes an inflatable hollow bag body provided with an inflation port and a line hole, a plurality of first fixing portions having perforations or hook portions and arranged on an inner wall of the bag body, and a light string system. At least an end portion extends out of the bag body from the line hole, and the remaining portions are arranged inside the bag body and fixed among the plurality of first fixing portions so that the light string system is unfolded into a preset shape in the bag body after the bag body is inflated. The light string system can be directly hung among the plurality of fixing portions, and can also be fixed among the plurality of fixing portions by a reinforcing strip or reinforcing line.