The outgassing of non-metallic materials in optical vacuum system will produce molecular contamination, which will lead to the decrease of transmittance of optical elements, and then aggravate laser-induced damage and reduce the load capacity of high-power laser facilities. In this paper, it is proposed to optimize the sealing materials in the laser environment, and carry out the experimental study of thermal vacuum baking. The results show that fluoroelastomer 246 has low outgassing, and temperature has great influence on the degassing effect of the material, and the vacuum baking degassing of the sealing ring has little influence on the optical characteristics. Compared with the sealing ring without vacuum baking, the average UV transmittance change decreased by 1 order of magnitude, and the average damage density decreased by 56%. This technology can be used in high-power laser facilities for precision cleaning and other optical cleaning systems.