Abstract: As an absolute measurement for the homogeneity of optical glass, the interference measurement is widely used because it can eliminate the form errors of both the interferometer reference surface and the part to be measured. The interference method to measure the homogeneity of optical glass was investigated, the error induced by material cutting angle was analyzed, and the method to correct the error was proposed. The stitch algorithm to measure the homogeneity of optical glass was also studied. The accurate measurement for the homogeneity of large-aperture optical glass was realized with a small-aperture interferometer.