Abstract:UHMWPE was modified with 16 inorganic compounds as additives. Friction coefficient of pure and modified UHMWPE was investigated by an UMT-3 microtribometer against a Ф3 mm 100Cr6 steel ball which was the upper counter mating specimen, under load of 98 N, with rotation rate of 60.18 mm/s and rotating radius of 0.5 cm for 60 min in dry friction, respectively. Width and depth of wear scars were determined and the analysis of XRD of worn surfaces wais also observed. Results show that average friction coefficient of modified UHMWPE with 5% and 10% WS2, 15% ZrO2 and 5% AlN are less, and they are suitable for dry friction condition and steel pairs. Width and depth of wear scars, friction of modified UHMWPE with 5% Ag2S, 10%Al2O3 and 15% N4Si3 are obviously less than that of pure UHMWPE, their XRD patterns between worn and unworn surfaces are same, and it is suggested that their crystal types are not altered during minor wear process.