To obtain a good C/C composite which has high mechanical properties, we concerned that the change of dimension of reinforcement as we proceed this research and we made a C/C composite by the way which reinforced PAN(Polyacrylonitile) based carbon fiber (as it stands) and fabricated carbon fiber. Also, to prevented that degraded the properties of C/C composite by the reduction during the carbonization process, added carbon black to matrix and the experiments were performed under various content(wt%) of carbon black. The Apparent density, ILSS, Flextural strength and modulus were evaluated to characterize mechanical properties of the C/C composite. It was found that UD and 2D composite which was added 10 wt% carbon black has good mechanical properties compared to that before addition while that were decreased as results of adding above 10 wt% since that decreased the bonding ability of CF and matrix.