A study is made of the muzzle flow field and the influence on the projectile flying of the su-per-high firing-rate series launched weapon based on the ALE equation and chimera grids technology, in combination with dynamic grid method. The result clearly reveals that complex muzzle flow field structure of complicated gunpowder gas was formed in the process of the high firing-rate. In addition, under the same explosive charge,on the high firing-rate,the acceleration of the following projectile is far less than that of the first one. The following projectile outside the barrel,the gunpowder gas before the projectile expansion formed a low pressure area,while the pressure after the projectile is higher than the first,so that acceleration for the following projectile is greater than that for the first projectile. The simulation results provide some theoretical basis for the study of the rapid-fire strong coupling launch projectile force analysis.