A measurement method of glass refraction rate based on machine vision technology is put forward, to achieve fast and high precision measurement requirements of glass refractive index. A mathematical model for measuring the refractive index of glass, the self-collimator can realize the function of the traditional V prism collimation, which calibrate the V-slot clamping posture. The large field of stitching is achieved by dual CCD and prismatic decomposition. The angle of the refracted light is directly measured by digital image technology. Finally, the test prototype is established, which is test and verified with traditional V prism refractometer and the digital V prism refractometer in the measurement accuracy and measurement time of glass refractive index, the results show that the measurement accuracy is better than ±2×10-6and measurement speed is better than 10 s, Whether both the measurement accuracy and the measuring time is better than before. It has important practical significance to realize fast and high precision measurement of refractive index of optical glass.