To improve the measurement accuracy of refractive index of parallel transparent materials, a refractive index measurement method based on Tolansky interference is proposed. Through the analysis of geometric optics theory,the relationship between the lateral displacement of the center of the Tolansky interference concentric ring and the refractive index was established. A parallel transparent material refractive index measurement simulation model was constructed, virtual experimental research on the measurement method was conducted, and the feasibility of the method was examined. An experimental system was built to measure the refractive index of glass sheets, which was compared with other instruments. The experimental results show that after measuring the material rotation angle, interference ring center lateral displacement, and material thickness, the relative error between the calculated refractive index value and the theoretical value is only 0. 11%, providing a new feasible solution for high-precision measurement of refractive index. The uncertain evaluation results indicate that the measurement results of this method are most affected by the thickness of the tested material.