Abstract: In order to obtain the optimal recoil resistance force to improve firing stability of gun, the dynamic model of overall gun system based on multi-body system dynamic modeling theory was built. By defining the minimal jumping height of during the firing period as optimal objective and the diameters of taper segments of control rod as design parameters, the problems are resolved through optimal design method. The optimized results indicate that the maximal recoil resistance force and jumping height are reduced after optimized. The recoil resistance curve is more smooth, at the same time, the firing stability of gun system is considerably improved.