Abstract: The ultra-high molecular weight polyethylene (UHMWPE) composites filled with polypropylene (PP) and MoS_2 of different compositions were prepared by compression molding at elevated temperature. The friction and wear behaviors of the composites sliding against AISI-1045 steel were evaluated on an MM-200 friction and wear tester in a ring-on-block configuration. The morphologies of the worn surfaces of the UHMWPE and its composites were observed on a scanning electron microscope. It was found that the incorporation of PP was beneficial to improving the processing performance of UHMWPE. The tertiary composite 72.7%UHMWPE/18.2%PP/9.1%MoS_2 showed and much better anti-fatigue ability mechanical properties comparable to those of the UHMWPE. The UHMWPE was characterized by severe adhesion and fatigue as it slid against the steel for an extended duration, while the tertiary composite by mild plastic deformation. This was supposed to be related to the enrichment and film-formation of the peeled off MoS_2 on the worn surface of the composite block or the counterpart steel ring.