The utility model discloses a power transmission device for a wheel mill, which mainly comprises an explosion-proof electrical motor, a worm screw speed reducer, wherein, the explosion-proof electrical motor is connected with the worm screw speed reducer through a shaft coupler. The utility model is connected with the wheel mill into integration through a shaft coupler. An auxiliary machine and components reduce about 60 percents, and the effects of low cost, easy manufacturing, easy installation, convenient maintenance and safety are achieved. The building area of working houses is reduced, and factory construction cost is lowered. The utility model thoroughly solves the hidden dangers existing in transmission shaft over wall and the open transmission of bigger and smaller bevel gear wheels.