There was a problem in current cell gap measurement of liquid crystal (LC) lens. A method was proposed by adopting interference of linearly polarized light in this paper. It was claimed that the incident light was monochromatic light with a uniform distribution of light intensity. The polarization axis of the analyzer was perpendicular or parallel to the polarization axis of polarizer. The difference between light and dark interference fringes was the biggest when the angle was equal to 45° between the rubbing direction of alignment layer in the LC lens and the polarization axis of polarizer. The cell gap of LC lens can be calculated by the transmittance of LC lens center and the max transmittance of its other locations. The tilt angle was equal to the pre-tilt angle of LC at the LC lens center. This method was simple and reliable. Its accuracy is relatively high due to the use of optical interference principle.