The invention provides a driving device. The driving device comprises a cam and a rocker arm, and also comprises an actuating mechanism, wherein the rocker arm is driven by the cam and is supported on a supporting shaft; the actuating mechanism is used for adjusting the position of the rocker arm and comprises at least one connecting rod, a crank and a guide supporting piece, wherein one end of the connecting rod is hinged with the middle part of the rocker arm through a supporting pin shaft; the other end of the connecting rod is hinged with the crank; the other end of the crank is hinged and supported to the supporting pin shaft; the guide supporting piece is provided with a work curved surface; and the part where the connecting rod and the rocker arm are hinged with each other is supported on the guide supporting piece movably. Because of increasing the adjustment of the opening stroke of a suction and exhaust valve of an air cylinder of an internal combustion engine by the actuating mechanism, the driving device has high capacity of adjusting the opening of the suction and exhaust valve. Because the stroke of the valve depends on the lift range of the cam and the structural parameter lever ratio (L2/L1) of the rocker arm, so the characteristic of changing the lift range of the valve is achieved by adjusting cam lift range curve parameters and rocker arm structural parameters.