Abstract: Microstructure of C/C composites with resin-derived carbon and rough laminate pyrocarbon was studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM). And effect of microstructure on frictional properties was discussed. TEM and SAED results showed that the resin-derived carbon near the carbon fibers was highly graphitized, which conferred appropriate and stable friction coefficient on composites. Because of the visible cracks between resin-derived carbon lamellae and the isotropical carbon beyond the carbon fiber, resin-derived carbon was readily destroyed by shearing. This gave a birth of a large number of chippings and disturbed the dynamic equilibrium . The high wear rate of the composites was the main problem for the application as a braking disc.