In order to study the structural integrity analysis of finocyl grain for solid rocket motor under the ignition loading, a numerical simulation method with considering the three-dimensional damage viscoelastic constitutive was proposed. The commercial finite element software was taken to the secondary development, and the user subroutine was written. Therefore, the numerical simulation was carried out. The distribution of stress, strain and displacement filed of finocyl grain were obtained under the condition of the temperature loading and ignition pressure. Results show that the deformation mode of inner surface of grain is different under the temperature loading and ignition loading. However, regardless of the temperature loading or ignition loading, both the Von Mises stress and Von Mises strain in the fin-slot region of grain are higher than those in other parts. This method can be applied to the security assessment of structural integrity analysis of solid rocket motor.