Abstract: A new kind of atomic oxygen simulator is used to test materials used in the magnetic torquer in this paper. Mass loss measurement and FT-IR analysis are used to obtain SAML and surface composition change of samples. Results indicate that vacuum exposure will lead to mass loss of materials, but the extent of loss for four tested materials sees a huge difference up to twenty four times. As for the mass loss after atomic oxygen exposure, the difference of the extent reaches twenty five times. Silicone can react with atomic oxygen to form a protective coating for preventing more atomic oxygen erosion. FT-IR analysis indicates that nitrogen group disappears on the surface of epoxy after atomic oxygen exposure, and O content increases. For silicone, the chemical bonds are broken and are turned into new kinds of O-H and C-H bonds.