Abstract: Short fiber reinforced EPDM inhibitor film is used for a new winding coating process, which is mainly to solve the reliable problem in free loading solid rocket grains with complicated structure. Based on fiber reinforced continuum mechanics theory, a simple anisotropic hyperelastic constitutive model is proposed to describe their large deformation, highly non-linear and strongly anisotorpic mechanical behaviors in the work process of solid rocket motor. The unitvolume strain energy function is decomposed into two parts:representing the strain energy from isotropic rubber matrix and anisotropic fiber tensile deformation. By introducing fiber direction to modify fiber strain energy, the specific method of obtaining model parameters by uniaxial and off-axis tension data is presented.Results show that it is highly suitable to characterize their anisotropic mechanical behaviors in the fiber direction from 0° to 45° and the error is less than 5% compared with experimental data. It is concluded that the proposed model is highly accurate and easy to achieve numerical development, which can provide theoretical basis for the structural integrity analysis of solid rocket motor.