In order to study the mechanical properties of propellant, the static stress-loading simulation of several kinds of typical gun propellants was carried out with the professional software ANSYS. The results indicate that when the static stress is loaded along with the axes of propellant grain, the transfiguration of the grain is inconspicuous. When the static stress is loaded along with the radial direction of gun propellant grain, the flaws in the gun propellant starts form from interior of the grain, then transmit to the exterior of the grain. And the fragmentation of gun propellant grain concerns with the shape of the grain and the position of the holes in the grain. The result of stress-loading simulation of gun propellant can be used in the production and application of propellant.