Abstract: Two kinds of high strength graphite with different hardness and strength were irradiated by γ-ray, and then friction test was carried out on the friction pairs composed of the graphite and SA 508 steel. The effects of load and lubrication conditions on tribological behavior of high strength graphite were studied, and wear mechanism was analyzed based on the wear morphology. The results show that, dry friction coefficient of the graphite with relative low hardness and compressive strength was small at low load, and the friction was stable. Dry friction coefficient of the graphite with relative high hardness and compressive strength was small under moderate load, and the friction was stable. Under wet friction condition, friction coefficient and wear loss of the graphite with relative low hardness and compressive strength at lower load were small, and friction coefficient and wear loss at higher load were larger. The hardness, compressive strength, flexure strength and tribological properties of high strength graphite were almost unchanged after irradiation. Under dry friction condition, the wear mechanism of high strength graphite was abrasive wear, accompanied by fatigue wear; Under wet friction condition, the wear mechanism was abrasive wear and erosive wear.