The automatic deduction method to overall transfer equation and rapid simulation of launch dynamics of Multiple Launch Rocket Systems (MLRS) are the key to the dynamic design of MLRS. For a new type MLRS, the multibody system launch dynamics model and its topological graph are developed. According to sign conventions and transfer equation of elements, an automatic method to develop the overall transfer equations for the new type MLRS is developed. The modeling efficiency and programming level are improved. The visual simulation system for dynamics of MLRS is established, and the launch dynamics are simulated rapidly and validated by test. The theory base for dynamic design of a new MLRS is provided.