Abstract: Carbon nanofibers(CNFs) were grown on a carbon fiber preform that was then densified by chemical vapor infiltration to prepare CNF-modified C/C composites.Micro-friction tests were used to investigate the effect of the CNF modification on the tribological properties of the composites at reciprocating abrasion rates from 600 to 1400 cycles/min over a distance of 15 mm and under a load of 60 N.Results show that the friction coefficient and the depth of the surface disturbed by the friction on the modified composites are not as sensitive to the rate as are the un-modified ones.When the rate is less than 1000 times/min, the modified composites have lower friction coefficients than the un-modified ones.The modified composites show steadier braking and their wear rates are much lower than the un-modified ones under the same rate.The wear debris formed from the matrix composed of CNFs and high-textured pyrocarbon helps maintain a high coefficient of friction and stable braking by forming a uniform film at the friction surface, resulting in the improved tribological properties.