In order to increase the connect reliability between the core stage and the boosters of the launch vehicle, the boosters with large fineness ratio can use hyper-static strap-on style. However, it may increase the analysis difficulty of the dynamic characters. Therefore, the dynamic model of booster with hyper-static strap-on style was established, and the bi-linear stiffness spring was employed to simulate the strap-on equipment. The dynamic response of the booster by the radial impulsion will be researched. The responses, including generalized displacements, frequency and the internal force will be compared with the static strapon style. Research results can provide reference and theoretical support for the engineering application.