The invention discloses a blasting demolition device of a cylindrical steel column structure building. The blasting demolition device of the cylindrical steel column structure building comprises a first concrete block and a second concrete block, wherein the first concrete block and the second concrete block are positioned in a cylindrical steel column. The first concrete block is positioned abovethe second concrete block, guide pipes are arranged on the first concrete block and the second concrete block, an air inflation bag is arranged under the second concrete block, an air inflation pipeis arranged on the air inflation bag, the air inflation bag is connected with a plurality of medicine bags through strings, the bottom ends of the strings are connected with sink blocks, the cylindrical steel column under the air inflation pipe is filled with water, and nonel detonators of the medicine bags are led out through the guide pipes. According to the blasting demolition device of the cylindrical steel column structure building, a notch is formed in the steel column in a cut mode, liquid water is injected into the notch, the medicine bags and the air inflation bag are placed into thenotch, a thin layer of concrete is arranged on the air inflation bag first in a pouring mode, after the concrete is solidified, the concrete pouring is continuously carried out, the liquid water is sealed in the steel column through the concrete, the medicine bags is detonated, and the incompressibility of the liquid water is utilized, so that the blasting damage degree is greatly improved, and the blasting effect is guaranteed.