Abstract: To improve the atomic oxygen (AO) erosion resistance of the silicone coating, hybrid coating was prepared on the polyimide substrate by aminopropylsilsesquioxane(APOSS) cross-linked epoxy silicone resin. The surface morphology, chemical composition and chemical structure of the hybrid coating were analyzed before and after AO exposure in a ground atomic oxygen simulated facility. The results show that APOSS can prevent the micro-cracks in silicone coating and avoid the “undercutting” phenomenon, and the mass loss of materials decreases obviously. During AO exposure, O and Si elements in APOSS changed slowly from the low-energy state to the high binding energy state (oxidation state), while a protective layer of SiO₂ formed on the coating surface and prevented the further AO erosion of the materials.