Abstract: In view of the structure and the optical system of the typical satellite remote sensor working intermittently in space, the paper analyzes the weak link of the optical system with regard to the radiation protection. Based on the simulation analysis of the total dose on the optical system, an approach of adding a protective cover at the baffle’s entrance is proposed to reduce the absorbed radiation dose where the largest dose is predicted, and the design of the protective cover is optimized through the simulation. It is shown that the radiation dose on the optical element is in a non-uniform distribution at different positions of the remote sensor, and the radiation dose on the first mirror used for receiving the object information is the largest. After installing the protective cover, the absorbed dose is decreased remarkably to a similar order of magnitude as that on the other parts. The protective cover has the best effect when it is 1 to 3 mm in thickness, and less than 20 mm away from the baffle’s entrance. This method of the radiation protection can be widely applied with practical technical specifications.