The invention discloses an auxiliary dismantling device used for a tower crane. A tower is formed by sequentially connecting and building a plurality of standard sections in sequence. A balance arm isarranged on one side of the tower. A winch is arranged on the balance arm. A triangular support is arranged on the other side of the tower. A first connecting plate is arranged between two lever arms. A lifting ring is fixedly mounted on the first connecting plate. After the arm rods are dismantled, the other ends of the lever arms are connected with a rotary mechanism through hinge heads correspondingly, and a second pulley is mounted on first connecting rods through bearings correspondingly. According to the auxiliary dismantling device used for the tower crane, the triangular support is arranged on the rotary mechanism, the standard sections of the tower crane are dismantled by means of the triangular support and the original tower crane winch in a matched mode, the problem that the tower crane fails to be dismantled spontaneously when the space is insufficient is solved, and the cost input for dismantling of the tower crane is greatly lowered; and after one group of standard sections is dismantled, the ground construction personnel transfer the standard sections, meanwhile, the triangular support is utilized for continuing dismantling of the next group of standard sections, and the tower crane dismantling efficiency is improved.