Abstract: The basic experimental research on the lubrication characteristics of rolling bearings usually adopts the ball-on-disc contact equivalent model testing technology. However, due to the lack of contact characteristics between the rolling element and the outer ring of the bearing, there is a significant gap between the measured results and the real bearings, and the obtained laws cannot be extended to the design and application of real bearings. The ball-on-ring contact equivalent model simulates the geometric contact form of the rolling element and bearing outer ring of a rolling bearing through the formation of friction pairs between steel balls and optical glass rings, which is closer to the geometric contact form of the rolling element and bearing outer ring. It plays an important role in clarifying the lubrication mechanism of rolling bearings. In order to perform optical visualization test on the lubrication characteristics of rolling bearings, the outer ring needs to be replaced with transparent material. However, there is a problem of difficulty in focusing the optical path when the rolling element contacts the transparent outer ring. The transparent outer ring of rolling bearings has different radial and axial shapes, so that its ability to deflect beams is different, resulting in unequal optical paths for radial and axial light rays, interference images cannot be focused simultaneously in both radial and axial directions, making it extremely difficult to obtain clear interference images. As a result, the research on lubrication tests under this contact form is limited. This paper used the optical design software ZEMAX to construct an optical system in which a steel ball contacted the glass ring that matched the measurement system. Designing the compensation lenses through optimization function, comparing the RMS radius of the spot (root-mean-square radius of the spot, used to describe the size of the spot) with the Airy spot (a diffuse spot formed by the diffraction limit at the focal point of a light source), according to the Rayleigh criterion, when the RMS spot falls within the Airy spot, it could be considered that the imaging quality of the optical system was perfect. When the spot size exceeded the Airy spot size, it was considered that the aberration of the optical system was large and the imaging quality was low. In this way, the optical system was calibrated and analyzed, and the parameters of the compensation lens under clear interference images were obtained. The results showed that the range of use of compensation lenses was related to the curvature and thickness of the glass ring. When using glass or sapphire outer rings for visual measurement of bearings, when the curvature radius of the glass ring was large or the glass thickness was thin, the film thickness could be directly measured without using compensating lenses. At this point, the image acquisition system had the ability to capture clear interference images; On the contrary, compensation lenses needed to be added, and the compensation lenses should be designed according to the bearing size. The comparison between the simulation results and experimental measurement results showed good consistency, indicating that the simulation system could achieve accurate simulation of the corrected optical path. This simulation system provided a new analytical method for the research of issues related to ball-on-ring test devices and full bearings, and had guiding significance for the selection of optical components.