The launcher models used in most of the previous studies have few degrees of freedom that cannot possibly capture many important motion characteristics. In this work, a flexible multibody model of a missile launcher system is built. The fixed, azimuth and elevation platforms and the launching pod are modeled as flexible bodies. Both the normal vibration modes and constraint modes are considered. Modes that do not contribute significantly to the total strain energy are eliminated to reduce simulation time. The joint flexibility effects are also included to the model by spring-damper elements. For the plume force and the motor thrust, experimental data are utilized. The forces transmitted to the base of the launcher system and the azimuth platform displacements during the launch are determined. Launching tests show good conformity with the simulation results, thus revealing that the developed model provides a realistic representation of the system.