Abstract: Ultra high molecular weight polyethylene(UHMWPE) based composites filled with nanometer ZnO wereprepared by heat compression molding.The influence of nano-particulates on the friction and wear behavior of thecomposites were investigated on a pin-on-disc test rig.The worn surfaces of the composites were observed on ascanning electron microscope.Itwas found thatthe friction and wear properties of the composites filled with15% ~20%nano-ZnO were improved remarkably.Wear mechanisms of the composites varied with the amount of nano-par-ticulates.The wear mechanisms of pure UHMWPE were adhesive wear and fatigue wear.Characteristics of fatiguewear disappeared gradually with the increase of mass fraction of nano-ZnO.When the fraction exceeds 15%,mainwear mechanism was adhesive wear.There were two zones on the wear surfaces,one was lack of ZnO,the otherwas abundant in ZnO,and the latter distributed in the zone lack of ZnO in the form of islands.