The dynamic characteristics of traction gear transmission system have great influence on the safety, comfort and reliability of EMU. Base on acoustic-structural coupled theory, the noise radiation characteristics of gear transmission system in high-speed train CRH380A are researched by finite element-boundary element method. Based on the multi-body dynamics theory, the dynamic meshing characteristics of the gear transmission system are revealed by RecurDyn. The natural frequency and the natural mode of vibrating are analysed for system by finite element method, and the vibration response curves of transmission gears under continuous working conditions are solved by modal superposition method. Furthermore, the radiated noise is predicted based on the acoustic radiation analysis model constructed by the acoustic BEM and Helmholtz boundary integral equation. The research results can provide theoretical basis for the optimization design of the low noise gear in EMU.