Composite nanoparticle additives of hybrid layered double-hydroxide/graphene nanosheets (LDH/GO) and layered double-hydroxide/molybdenum disulfide (LDH/MoS2) have been fabricated by electrostatic self assembly. The morphologies and compositions are confirmed by FESEM, EDS, XRD, Raman, and FT-IR Zeta potential testing confirms that the composite nanoparticles have good dispersion stability in poly-alpha-olefins-4 (PAO-4). Meanwhile, the nanocomposites as additives can dramatically enhance the lubricating properties of PAO-4. Research results indicate that the good friction and antiwear properties of LDH/GO and LDH/MoS2 composites can be attributed to the synergistic lubricating effects between LDH and GO or MoS2.