A facile electrostatic self-assembly way was developed to prepare Cu nanoparticles @ rGO (reduced graphene oxide) nanosheets to enhance the properties of PI (polyimide) composites. Through the electrostatic selfassembly between Cu and rGO, interface compatibility of Cu and PI matrix was improved. Meanwhile, the zero-dimensional Cu and two-dimensional rGO in core-shell Cu@rGO hybrids could integrate the multiple advantages and provide synergistic enhancement for PI composites. As a result, the maximum thermal decomposition temperature of PI/Cu@rGO composites recorded an increase of 12 degrees C in comparision with that of pure PI. In addition, the Cu@rGO hybrids demonstrated the optimal lubrication properties for PI matrix compared to individual Cu, rGO and Cu/rGO blend. For PI/Cu@rGO-0.5 wt% composites, the specific wear rate and average friction coefficient were decreased by 44.1% and 11.6%. The outstanding tribological performance of PI/ Cu@rGO composites can be ascribed to the synergistic enhancement between Cu nanoparticles and rGO nanosheets as well as the formation of high-quality transfer film. Furthermore, the inherent abrasion mechanism of PI/Cu@rGO composites was explored systematically.