Abstract： A model was established to predict the longitudinal tensile modulus of short-fiber-reinforced rubber (SFRR) sealing composites, which incorporated the interphase, the fiber and the matrix. The Mori-Tanaka method was employed to calculate the longitudinal tensile modulus of SFRR and the calculation results were compared with the experimental data. Moreover, the effects of fiber volume fraction, interphase thickness and interphase modulus on the longitudinal tensile modulus were discussed. The results show that calculation results of the longitudinal tensile modulus are in good agreement with the experimental data and the relative error is less than 11.2%. The longitudinal tensile modulus of SFRR increases as the fiber volume fraction increases. The interphase modulus has a significant effect on the longitudinal tensile modulus of SFRR. The longitudinal tensile modulus of SFRR increases as the interphase thickness increases when the interphase modulus is less than the matrix modulus, and decreases when the interphase modulus is larger than the matrix modulus.