Abstract: In view of the fact that the CCD is expensive and the supporting equipment is more, in the laboratory measurement, the CCD measurement system is replaced with a 20-fold reading microscope.In this paper, the linear array CCD method of measuring refractive index of glass material is improved.On the optical bench, using the reading microscope, by measuring the oblique incidence to the parallel plate glass between the exit light and incident light of transverse offset, we can measure the refractive index of the medium.