Abstract: A micromechanics based model of bridging fibers was established to study the effects of interface on the tensile modulus and strength of the fiber reinforced ceramic matrix composites. The coefficients of fiber stress uniformity and interface debonding rate were int roduced to characterize the property of the interface with complete debonding and partial debonding, respectively. The result indicates that the higher the coefficients, the lower the modulus while the higher the stress carried by the fibers when the composites fracture. Based on the rule of mixtures, a new strength calculation model was presented. The effects of matrix crack distribution, interface debonding and fiber pullout on the tensile strength were discussed. The results predicted by the model are in good agreement with the experimental data.