The friction and wear behaviors of neat PI and carbon fibers reinforced polyimide (CF/PI) composites were investigated at various temperatures. The results showed that the introduction of carbon fibers could greatly improve the wear resistance in the whole temperature range, while the friction coefficients strongly depended on sliding temperatures. The lubricity of carbon fibers was only found occurring at high temperatures of 180–260 °C, which can be attributed to the graphitization of carbon fibers that promotes the generation of friction and transfer films with excellent lubricity on the worn surfaces. This study is expected to provide guidance for the application of carbon fibers both as lubricating and reinforcing additives in polymer matrix sliding at high temperatures.