The invention relates to a mold force arm device for improving glass hot bending forming. The device is composed of a main force arm assembly, a starting force arm assembly and a limiting assembly. The main force arm assembly comprises a main force arm, a heavy hammer with which the main force arm is sleeved, and a limiting cross bar connected to the main force arm. The starting force arm assembly comprises a starting force arm connected with the bottom end of the main force arm through a loose joint, and a heavy hammer with which the starting force arm is sleeved. The starting force arm is erected on the limiting cross bar. The limiting assembly comprises a starting force arm branch and a main force arm limiting block which are connected to a die base. Compared with the prior art, the hinge bending speed can be controlled, it is ensured that the hinge bending speed and the glass die sticking speed are synchronized, and the glass forming quality is improved.