Abstract: The low energy friction and wear properties of carbon/carbon(C/C) composites uses for aircraft brakes were studied,curves of relationship between the moment of brake force and brake velocity were analyzed, and the essential caase was discussed of why C/C composites possess a maximum friction coefficient when energy is changed. The results show that the maximum friction coefficient is decreased as the specific pressure is increased. The friction surface of C/C composites is rougher in low energy condition. The wear rate is about twice as large as in normal energy conditions.