The orthotropic material has been widely applied in large solid motors. In order to reduce the Von Mises strain, and greatly improve the structural integrity of solid motors, the star grain is taken as an example. The orthotropic material parameters sensitivity analysis of elastic modulus and Poisson's ratio of propellant and insulation blanket are studied. The orthotropic material parameters sensitivity coefficients of solid motor grain are obtained. The methods and conclusions are helpful for the designers, manufacturers of solid motors.