A drive mechanism for a medication delivery device includes a motor, a housing, a gear cover, a gear transmission system, a helical transmission system, and a sensor system. The helical transmission system includes a plug, a screw shaft, and a sliding block connecting the plug to the screw shaft. The gear transmission system includes a first gear disposed on an output shaft of the motor and a second gear disposed on one end of the screw shaft. Dual gears interconnect the first and second gears. The motor drives the plug along a linear path by rotating the screw shaft via the gear transmission system, causing the sliding block to move along the screw shaft. The sensor system monitors the driving process. The plug provides the force required to effect the dosing of the medication.
