Abstract: Materials used on spacecraft’s outside surfaces are subjected to many environmental threats of property degradation, among which the atomic oxygen is one of the most important. Organic silicon atomic-oxygen-protection film was prepared by using the method of polymerization. The effects of the preparation processing on the film structure and its durability are discussed, including the principle of the polymerization, the film structure and the composition of the film. The film is tested in our ground based atomic oxygen simulator, and the results indicate that the film enjoys a good performance.