In order to improve the life and firing accuracy of rocket launcher, the modal test of rocket launcher system is carried out by experimental modal analysis method. The modal parameters such as the natural frequency, modal shape and damping ratio of the structure are obtained, and the vibration characteristics of the system under different tire pressures and support heights are analyzed, which provides a basis for the vibration characteristics analysis, vibration fault diagnosis and prediction, and the optimization design of the structural dynamic characteristics of the rocket launcher structure system. The modal test process is simplified, and the modal vibration parameters obtained from the test are compared with the finite element simulation results. The simulation results verify the accuracy of the finite element analysis and improve the application value of the computational modal analysis.