Abstract: The vibration response of the rarefaction wave launch device was studied.Based on the launch mechanism and structure characteristic of the rarefaction wave launch device, the vibration equations of launch device were established in consideration of the actual movement of the projectile and inertial breech.In these vibration equations, the projectile and inertial breech were equivalent to the moving masses, and the coupling effects between elastic vibration of the launch device and rigid movement of the moving masses were also considered.With modal superposition method, the vibration equations were dispersed to the second-order time-variant equations.After numerical calculation, the vibration response and muzzle dynamic effects were acquired.From these results, some theory references for fire precision and airframe integration design were provided.