Magnetic reduced graphene oxide/Fe3O4 (RGO/Fe3O4) composites were synthesized via chemical co-precipitation method. The RGO/Fe3O4 were characterized by field-emission transmission electron microscopy (FETEM), X-ray diffraction (XRD) and Raman spectrometry and magnetic property measurement system (MPMS), respectively. Polyalphaolefin (PAO) 6 with different contents of RGO/Fe3O4 was prepared by a dispersion process. The tribological properties of PAO 6 containing RGO/Fe3O4 were evaluated using a tribometer. Friction results indicated that RGO/Fe3O4 can significantly improve the tribological properties, especially anti-wear properties, of PAO 6. From the analysis results, RGO/Fe3O4 possibly repairs the worn surface by forming an effective tribofilm, which benefits from the synergistic effect of RGO and Fe3O4 from the RGO/Fe3O4 nanocomposites. Schematic diagram of preparation process of PAO 6 with RGO/Fe3O4. Display omitted •Magnetic RGO/Fe3O4 composites were synthesized.•RGO/Fe3O4 improved the tribological properties of PAO 6.•The role of RGO/Fe3O4 was ascribed to form tribofilm.