Abstract: C/C composites with different carbon matrix were prepared by three kinds of process,and then surface pores of the composites were sealed by chemical vapor deposition and resin-infiltration-solidification.The sealing performances of the composites were studied.The resuts show the static pressure leakage of the composites relates to the method of sealing surface pore,the density of the composites and the pressure of the sealed medium.The method of sealing surface pore plays main role in sealing,and the leakage for the composites sealed by resin-impregnation-solidification more than two times is zero under the test conditions.The higher the density of the composites,the lower the pressure of the sealed medium,the little the leakage.Besides,running leakage is also related to the matrix carbon of the composites.For the composites with the matrix of resin carbon,the higher the density,the better the sealing of surface pore,the little the leakage during running.The wear loss of the tested composite specimen is little,the most of the loss is only 0.002 5 mm for the sample with resin carbon matrix after running for 5 h.