Abstract: Wear and friction tests were conducted by a CBZ-1 tester under dry sliding to analyze and research the tribological properties of aged UHMWPE. The hardness of samples under different aged conditions and friction heat generated at different sliding velocities were examined, worn surfaces of samples were observed by scanning electric microscopy, the surface roughness of the coupler was analyzed by interference profilometer, and friction mechanisms of UHMWPE under different aged condition were investigated. The results show aging had an obvious effect on the dry sliding performance of different molecular weight UHMWPE. The friction performance of UHMWPE gradually deteriorated as the aged time and aged temperature increased. The friction heat generated at high velocity further aggravated the friction performance of UHMWPE under certain aged conditions. The wear mechanisms of UHMWPE were mainly fatigue wear and abrasive wear when the aged temperature were 40 ℃, 60 ℃ and the aged durations were 120 h and 240 h. At 80 ℃ and 480 h, 600 h of aged condition, the main wear mechanisms were adhesive wear and fatigue wear.