The work aims to explore effects of nano alumina (αAl2O3) and sulfonated graphene(S-GNS) on thermal conduc-tivity and tribological properties of polyoxymethylene (POM) composites and analyze the synergistic modification mechanism of αAl2O3 and S-GNS. S-GNS, αAl2O3 and POM were used as raw materials to prepare S-GNS-αAl2O3 complex by electrostatic self-assembly method, as well as S-GNS-αAl2O3/POM composites by compression molding. The S-GNS and S-GNS-αAl2O3 complexes were characterized by XRD, FT-IR and SEM. At the same time, the thermal conductivity, friction coefficient and wear loss of composites were tested by friction and wear tester and thermal conductivity tester. The worn surface morphology of the composites was observed by SEM. The synergistic modification of αAl2O3 and S-GNS could effectively improve the thermal conductivity of composites. When the content of S-GNS-αAl2O3 was 7% (mass fraction, the same below), the thermal conductivity of the composite was 0.2524 W/(m?K), which was 25.3% higher than that of pure POM. S-GNS played the role in transferring heat and improving the compatibility of interface between αAl2O3 and POM. The addition of S-GNS improved the thermal stability of S-GNS-αAl2O3/POM composite and effectively reduced the damage to the matrix by αAl2O3 abrasive particles. Meanwhile, the addition of αAl2O3 shared the load and improved wear resistance of composites. With the increase of S-GNS-αAl2O3 content, the friction coefficient of S-GNS-αAl2O3/POM composite decreased gradually and the wear amount also decreased. Furthermore, the worn surface was very smooth, and the wear mechanism was abrasive wear and slight furrow cutting. S-GNS and αAl2O3 can play a synergistic role in POM composites, and effectively improve the thermal conductivity and tribological properties of POM composites.