Abstract: The relationship between the microstructure and the interfacial properties of C/C composite was researched in this paper. The microstructure features of the interfacial layers in C/C composite obtained by high resolution Micro-CT were statistically analyzed , and the probability density function of the interfacial microstructure was achieved. Mechanical properties of the interfacial layers in C/C composite were calculated by a hypothetic analysis model. The distribution of mechanical properties can be obtained through introducing a probability density function of the interfacial microstructure into this analysis model. The mechanical properties of the interfacial layers in C/C composite were measured by the push out tests of fiber bundles. Comparing the calculation results with the experimental results, it is found that the means and dispersions of these two results are accordant.