Based on the constitutive relationship of viscoelastic material using the Burgers model and the corresponding viscoelastic finite element method, the finite computational models are established to value the effects of solid rocket motor material parameters on the structure integrity. They include the three-dimension model and the plane strain model. In the case of thermal loading, the three dimension model is necessary, but the plane strain model is accurate enough in the case of internal pressure. Then, the effects of solid rocket motor material parameters on its structure integrity are respectively compared and analyzed under internal pressure and thermal loading by the use of MSC/NASTRAN software system. Under thermal loading, the main factors affecting the motor structure integrity are the propellant Poission's ratio and thermal expansion coefficient. Under the internal pressure, the main factors are the motor liner Poission's ratio, propellant initial elastic modulus and Poission's ratio. These conclusions would be useful for to the design of solid rocket motors.