Cable-stayed bridge main tower dismantling method and multifunctional tower dismantling machine

The invention discloses a cable-stayed bridge main tower dismantling method and a multifunctional tower dismantling machine. The cable-stayed bridge main tower dismantling method comprises the steps that rails are erected on the two sides of a bridge tower, and a door-shaped support and an operation platform are installed; the door-shaped support is driven to climb to the tower top along the track, and two lifting devices are installed on the horizontal portion of the door-shaped support; after the hoisting holes are drilled, the top section of the bridge tower is cut in the horizontal direction, and then the top section of the bridge tower is cut into two bridge tower blocks in the vertical direction; using a lifting device to translate the bridge tower blocks on the same side outwards out of the range of the bridge tower and then lowering the bridge tower blocks to a bridge floor; and the door-shaped support is driven to move downwards, and the previous steps are cyclically repeated to dismantle the bridge