This work aims to study sliding electric contact characteristics of a pure carbon strip under high speed current-carrying conditions. The pure carbon strip was processed into a 120 mm×34.5 mm×25 mm rectangular sample. A series of experimental tests were carried out on a high speed ring-on-block tester. The effects of normal pressure, sliding speed and current on current-carrying efficiency were investigated. Wear appearance of carbon contact strip at different current-carrying efficiency was compared. During the tests, voltage, current on both ends of the contact pair as well as temperature rise of the carbon strip were collected in real time. Sliding distance of each test was 150 km, and wear appearance of the strip was analyzed with scanning electron microscopy (SEM). Provided with constant current, arc discharge energy decreased as the current-carrying efficiency increased. At the electric current of 150 A and sliding speed of 150 km/h, the current-carrying efficiency of a pantograph-catenary system increased as the normal force increased. At the electric current of 100 A and normal force of 100 N, the current-carrying efficiency of a pantograph-catenary system decreased as the sliding speed increased. At the voltage of 7 V and sliding speed of 150 km/h, the current-carrying efficiency of a pantograph-catenary system decreased as the electric current increased. Wear appearance of the strip indicated that, the carbon strip was mainly subject to mechanical wear accompanied by slight arc ablation at high current-carrying efficiency. However, the carbon strip was subject to very serious ablation accompanied by conspicuous ablation pits at low current-carrying efficiency. The current-carrying efficiency reflects contact stability of pantograph-catenary system to a certain extent. The lower the current-carrying efficiency is, the worse the wear of carbon strip is.