Because of the complex structure on the observation equipment, the maintenance staff are lack of understanding for new equipment. It is difficult to find the fault caused by optical parts fretting. So the staff can not offer the technical guarantee for new equipment. Aiming at this problem, by means of mathematical tools to express optical parts imaging laws. Studying the fretting theory and building the fretting model. With the computer simulation technology, combining with optical fretting theory and practical problems, producting a set of simulation software and showing the influence of optical parts fretting. The results show that the fretting of optical parts influence the imaging effect and firing accuracy. For the maintenance training of universal and serialized sighting telescope, the simulation research provides technical means.