Optical glass is the foundation and an important part of photovoltaic technology industry, and the dispersion coefficient is an important constant which responses performance. The novel mathematical model was reestablished instead of the traditional dispersion coefficient measurement formula based on CCD imaging and automatic alignment technique of machine vision in this system. The influence of refractive index of air was considered for dispersion coefficient measurement accuracy. In the design process of small multiband collimator, on the basis of adjusting the aberration related to aperture, the optical path of the light was calculated, which was characteristic sense for aberration in meridian inner surface, the location aberration was obtained between the ideal image and the actual image， the simulation of infinity goals was achieved by a small band collimator. Finally, the technique of multiband small parallel light pipe, automatic imaging processing and grating angular displacement measurement were applied in this system. The automatic image alignment of dispersion coefficient measurement system was designed and high precision measurement was realized. It can know from the accuracy of analysis that the measurement system is calibrated with the known dispersion coefficient of optical glass, and the results show that the absolute errors is less than ±2.309 3×10^-6.