Abstract: To study the different graded interfacial characteristics of fiber/matrix and fiber bundle/matrix for carbon/carbon composites, two sets of push ouTinstruments for evaluating the interfacial bonding properties were designed and established respectively. Meanwhile, by using the push out techniques, the relationship between the bonding strength of these two graded interfaces under different processing parameters of C/C composites was investigated and their effects on the tensile properties of C/C composites were discussed. ITis found that the fiber and fiber bundle push out test techniques established in this paper can be used to evaluate the different graded interfacial bonding properties of C/C composites quantitatively. The results reveal that the different graded interfacial bonding status provides different contributions to the macro mechanical properties of C/C composites to some extent.