The reaction mechanism of space silicone rubber coatings and atomic oxygen have not been fully grasped,the protective effect of silicone rubber are not completely clear.Then the ground-laboratory test samples were exposed to atomic oxygen environment in an electron cyclotron resonance facility,all samples were tested for appearance, mass loss,apparent morphology, surface composition and optical properties to evaluate the protective effect of space silicone rubber systematically. When the samples received flux of 4.9×10¹⁸ cm^-2 and 1.2×10²¹ cm^-2, the mass loss of the coatings are not increased as the atomic oxygen exposure time and the cumulative flux increase,the appearance and optical performance of the coatings are significant changed,and the coatings may prevent further reaction of atomic oxygen with the internal silicone rubber to provide good protection.It is found in the exposure test that cracks occur on the surface of the silicone rubber protective coatings under the atomic oxygen environment. Therefore, the space silicone rubber needs to be reinforced to improve its antigenic erosion ability. The article also showed that the traditional techniques for determining effective atomic oxygen aggressive exposure in ground-laboratory facilities based on mass loss measurement is not be applicable for silicone, and a new evaluation mechanism of silicone affected by atomic oxygen attack was proposed.