The design of dynamic scale model is one of the most important parts in the scale model test which is an effective approach to obtain dynamic characteristics of large launch vehicle. Taking the launch vehicle as the object, the similarity relationships for each part were derived on the basis of the structural components of the launch vehicle. Transverse dynamic similarity relationships of the launch vehicle were derived by taking advantage of the consistent similarity in respect of transverse stiffness and mass. Taking the actual processing and manufacturing conditions into consideration, the restrictions of similarity coefficient for transverse stiffness and mass were analyzed. According to the relationships and the restrictions above, a 1/5 dynamic scale model was designed and its similarity of dynamic characteristics was verified through the numerical analysis of finite element. The verification result shows that the 1/5 scale model gets a high-level similarity with the prototype in terms of dynamic characteristics, and the method can be effectively applied to the design of dynamic scale model for launch vehicle.