The high firing precision has been continuously required by modern war for weapon systems such as multiple launch rocket system, artillery, tank and armored vehicle. However, bad firing precision, huge consumption of rockets in test and launch unsafety are hard technical problems restricting the development of these modern weapon systems. The firing precision and the launch safety depend on dynamics of the corresponding weapon system. As an engineering subject studying the motion and force for weapon system during launch process, launch dynamics has been a novel sally port to improve the firing precision and to ensure launch safety of weapon systems. In this paper, the theory and technology of launch dynamics of multi body system as well as its applications in the design and test of firing precision and safety for weapon systems are studied. It can provide new theory and technology for the design and test of firing precision and safety of weapons．