The oleylamine (OA)-modified carbon nanoparticles (CPs(-OA)) with particle sizes of 25-35 nm were synthesized by a facile one-pot pyrolysis method. As the OA molecules were covalently attached on the surfaces of CPs(-OA), the CPs(-OA) exhibited good dispersibility in polyalphaolefin (PAO). Then the tribological behaviors of CPs(-OA) as the lubricating additives of PAO were investigated in detail. Under the four-ball mode and the load of 392 N, the CPs(-OA) showed the best friction-reducing and antiwear properties at the optimal concentration of 1.0 wt%. Specifically, in comparison with that of pure PAO, the mean friction coefficient and mean wear scar diameter of the 1.0 wt% CPs(-OA)/PAO suspension reduced by 47 and 30%, respectively. The friction-reducing and antiwear capabilities of CPs(-OA) strengthened with increasing load from 200 to 392 N and increasing test time from 240 to 480 min. In addition, the CPs(-OA)-based additives could work for a long time without weakening the lubrication capability. The synergistic effect of tribofilm, including PAO molecules and the CPs(-OA) layer, might account for the outstanding friction-reducing and antiwear capabilities of CPs(-OA)-based additives under boundary lubrication.