The utility model relates to a large-scale bearing lossless detaching device including a worm-wheel hub. The upper end and the lower end of the worm-wheel hub are respectively provided with an upper sealing cover and a lower sealing cover, the detaching device further includes a bearing pressing plate, a lining, a hopper, a thermometer, and an electric heater, the bearing pressing plate is connected with the lining through screws, the thermometer and the electric heater are arranged on the bearing pressing plate, the hopper is connected with the bearing pressing plate via a pipeline, and an O-shaped sealing ring is arranged between the upper sealing cover and the worm-wheel hub. The detaching device provided is advantageous in that (1) the integral structure is simple, the cost is low, and the operation is convenient; (2) the detachment of a bearing can be well protected through the slow heating of the bearing by lubricating oil; and (3) the interference between the inner ring of the bearing and a journal can be effectively eliminated, so that the bearing can be detached from the shaft of the worm-wheel hub by mean of deadweight, the bearing is detached in a protective manner and is free of any damage.