A control method of stabilizing the oscillation amplitude of a torsion oscillator is described. The method includes the steps of: driving a torsion oscillator at a predetermined frequency with a drive energy level by a control module to generate a scanning angle of the incident light beam, wherein the drive energy level is associated with the predetermined frequency; comparing the scanning angle corresponding to the drive energy level with a designate scanning angle by the control module; and adjusting the drive energy level based on the comparison result until the scanning angle of the torsion oscillator is equal to the designate scanning angle.