Seven modified nitramine double base propellants with different content of RDX were prepared by screw extrusion process, and their mechanical safety performance, including the friction sensitivity, the impact sensitivity and the shooting sensitivity were studied according to the national military standard methods. Results show that with increasing of RDX, the impact sensitivity, the friction sensitivity and combustion probabilities of shooting of the propellants increase. The friction sensitivity keeps stable at around 60% explosion probability and impact sensitivities increase slowly when RDX content is up to 27%.The combustion probabilities of shooting of the propellant increase with RDX content increasing.