Abstract: The present invention discloses a power transmission device, including a revolution shaft, a power transmission frame wheel rotatably and coaxially coupled to the revolution shaft, a plurality of spinning shaft symmetrically provided at outside edges of the power transmission frame. A plural of blades rotatably and coaxially coupled to respective spinning shaft, and a blade rotating arrangement connected to respective spinning shaft for managing a rotational direction and speed of the blades, such that when the revolution shaft is powered to rotate driving the power transmission frame into rotation, the spinning shaft provided at outer edges of the power transmission frame are capable of being rotated with a reversed direction with speed ratio of 1:2 for maximizing the wind bearing size of the blade in wind favorable condition and decreasing the wind bearing size in wind undesirable condition.