Abstract: The sliding friction and wear behaviors of C/C composites to be used in the seal ring of the main axis of turbine engines for airplane were tested on a MM-2000 ringblock frictional tester. The effect of preparation conditions, graphitization treatment in the final step, density, and carbon fiber direction in the composites on the behavior was investigated. It is found that after CVI, resin impregnation, densification and graphitization, the C/C composites have good tribology properties. When the composites are graphitized in the final step, their densities are higher and tribology properties are better than those of ungraphitized samples. When the load is moderate, the friction coefficient of perpendicular samples is higher than that for parallel ones, but the volume loss of perpendicular samples is lower than that for parallel ones. The C/C composite rings are superior to those made of high strength graphite for this application.