The optical wedge is a prism with a small apex angle, which is often used to control the deflection angle of the light beam or compensate for the deviation of the small angle of the light beam. A driving method for a kind of liquid crystal device driven by four electrodes with rectangular aperture to realize an optical wedge is proposed. The advantage of the liquid crystal wedge lies in its small size and light weight. The wedge angle can be controlled by voltage and the optical wedge can be rotated without a mechanical device. It is expected to be used in some fields where the deflection direction and angle of the beam need to be controlled, such as optical tweezers, lidar and so on.