Abstract: Aiming at the problem that the chromium-plated rifling land of gun could be worn badly during launching, the patterns of inner face and transverse section of gun tube, which has gone through the life firing test, were carefully analyzed. By exploring the destruction principle of chromium layer, several destroyed modalities of chromium layer on inner face of gun were summarized and the logic relations of destroyed process were set up. In addition, the propellant with nanometer wear additive was prepared for experiment. Test results prove that gun powder with nanometer wear additive could prevent wear of chromium layer remarkably. The use of powder with nanometer wear additive is an effective method to protect the chromium-plated rifling land and extend the life of gun tube.