The friction and wear behaviors of carbon and aramid fibers reinforced polyimide composites have been investigated in simulated space irradiation environment and start-stop friction process. The experiment results showed that the introduction of fibers decreased the friction coefficient and improved the wear-resistance of polyimide matrix after atomic oxygen and ultraviolet irradiations especially for the carbon fibers. A start-stop friction process aggravated the wear of various composite materials against the counterpart ball. Carbon fibers reinforced polyimide displayed excellent tribological property in irradiation environment and start-stop friction condition, which was expected to become a kind of potential tribological material for the application of spacecraft. (C) 2015 Elsevier Ltd. All rights reserved.