Abstract: The DLC films were prepared on the surface of C/C composites substrates by plasma enhanced chemical vapor deposition method. Friction and wear properties of C/C composites and DLC films were investigated with a ball-on-disk tribometer in dry air. The results show that the prepared DLC surface modification films were smooth and compacted. With increase of deposition time, the thickness of DLC films increased and the adhesion strength between DLC films and substrate decreased. The average friction coefficient and wear rate of C/C were 0.285 8 and 1.6×10-4 mm3·N-1 ·m-1, respectively. After surface-modified by DLC films, the friction coefficient of the substrates reduced obviously (0.08-0.27), and the wear rate also reduced by 1-2 orders of magnitude. And with the deposition time of the DLC film increasing, the friction coefficient and wear rate decreasd.