Abstract: At altitudes between 200 km and 700 km，atomic oxygen（AO）is the most abundant atmospheric species that，being highly reactive.It is now well established that the interaction between atomic oxygen in the low-Earth-orbit（LEO）space environment and spacecraft at orbital velocities causes severe mass loss from solar array materials，thermal control materials and optical materials，etc.Atomic-Oxygen-Protection technology is important for guarantee materials or components against atomic oxygen.This paper introduced atomic oxygen protection technologies and methods.