Wear of polyimide composite cage due to lubrication failure has a significant impact on the lifetime of bearing, but the related mechanisms are still far from understanding due to the complex movements of bearing parts, such as rolling, sliding et al. in the real operations. Here, the tribological behaviors of polyimide composite against steel ball were studied under a motion compounded with rolling and sliding in comparison with pure sliding. The rolling-sliding motion has a strong influence on the tribological properties of polyimide composite depending on lubrication conditions. Especially under PAO4 oil lubrication, the rolling-sliding motion can facilitate the degradation of polyimide composite, resulting in severe surface wear and aboundant black products forming. The analysis based on XPS and SEM measurements and the compared results from heating sliding test and thermal treatments indicates that the formation of black products is mainly attributed to the tribochemical reactions accompanying with the rupture of C-O and C = O bonds due to high frictional temperature. This process is further facilitated when the PAO4 oil and the metal from counterface participate in the tribochemical reactions. [GRAPHICS] .