Abstract: Five kinds of carbon fiber reinforced paper-based friction materials with 0.1 ~ 12 mm long carbon fibers were fabricated by paper-making process. The effects of carbon fibers length and orientation on thermal load and tribological properties were investigated by using a stepped power test method. Friction failure mechanisms were analyzed via combined use of the scanning electron microscope and thermal conductivity tester. The results show that the carbon fiber lengths and orientation had pronounced effects on thermal load capacity and tribological properties. The sample containing 6 mm long carbon fibers had the supreme thermal load capacity. Firm framework was set up by using 3~12 mm long carbon fibers as reinforcement, which guaranteed stable tribological properties under different power levels. Meanwhile, the carbon fibers length played an important role in fibers orientation. The thermal conductivity was improved and the max power flux was decreased when carbon fibers were perpendicular to friction surface.