Abstract: The friction and wear properties of polytetrafluoroethylene (PTFE) composites filled with nanocrystalline Al 2O 3 were evaluated with an MM 200 friction and wear tester. The worn surfaces of PTFE composites were examined by means of scanning electron microscopy (SEM). It has been found that the incorporation of nanocrystalline Al 2O 3 into PTFE increases the wear resistance of PTFE but worsens the friction reduction performance to some extent. The friction coefficient of PTFE composites increases with the increasing of Al 2O 3 content. The best wear resistance of the composite is reached at a mass fraction of Al 2O 3 about 10%. Moreover, nanocrystalline Al 2O 3 as the filler in PTFE leads to enhanced plastic deformation of PTFE matrix in the composite, which subsequently increases the friction coefficient.