Abstract: The polyimide ( PI ) composites filled with several solid lubricants were prepared by compression molding The surfaces of polyimide composites were irradiated by a certain doses of atomic oxygen The changes of surface structure of polyimide composites were characterized by Fourier transform infrared spectroscopy ( FTIR -ATR ) and X –ray photoelectron spectroscopy ( XPS ) before and after irradiation , while the tribological behaviors were investigated by using a UMT wear tester at room temperature under ambient atmosphere The surface and worn surface of the polyimide composite blocks before and after irradiation were observed by using scanning electron microscope ( SEM ) Results indicated that the matrix and fillers in the PI composite surfaces were oxidized to some extent , whereas the molecule chain of the Pl matrix and PTFE resin were partially destroyed during irradiation The surface of the PI composites became rougher than that before irradiation As a result , the friction coefficient of Pl composites increased The wear mechanism of Pl composites changed from adhesive wear before irradiation to slight ploughing and abrasive wear after irradiation