The invention provides a high-altitude demounting and modifying method of a jacking platform. The method comprises the steps that (a) in the high altitude, demounting and modifying units on the jacking platform are overall hoisted down through a tower crane; (b) after being close to the ground, the demounting and modifying units are exchanged and hanged to a truck crane from the tower crane; and (c) demounting work of the demounting and modifying units is manually carried out on the ground from bottom to top. Thus, by means of the method of combining high-altitude overall hoisting and ground demounting, the demounting and modifying difficulty of all systems forming the jacking platform in the high-altitude state is effectively reduced, meanwhile, occupancy on the tower crane is effectively reduced, and tower construction is prevented from being influenced.