The invention relates to a transmission device capable of sharing overload. The device is composed of multiple sets of main transmissions, each rack is provided with one set of the main transmission, and in each set of the main transmission, a main motor (6) drives the corresponding working rack (1) through a main deceleration system (2); each main deceleration system (2) is of a planet differential structure, a pair of bevel gears (4) and (5) are arranged between each set of the main deceleration system (2) and the main motor (6), and the bevel gears (5) are connected with the bevel gears of the adjacent racks through connecting shafts (7) and connected with a same overload motor (3); in each set of the main transmission, the main motor and the bevel gears connected with the overload motor simultaneously drives two input parts in the main deceleration system, and another part in the main deceleration system outputs the rotation speed and torque; the main motor and the overload motor jointly form the output rotation speed. According to the transmission device, each rack is still driven by the main motor separately, and flexible speed regulation can be achieved; meanwhile, the total installed capacity is greatly reduced, and energy sources are saved.