Abstract: Taking a certain double\|deck EMU with 16\|vehicle formation and speed of 350 km/h as the research object, the vehicle layout is optimized considering vehicle balance, and the lightweight design of components except vehicle body is carried out. A vehicle body finite element calculation model is established, the influence of parameter changes of vehicle body related parts on the mode is analyzed using control variable method, then the vehicle body structure is optimized and the modal frequency of vehicle in conditioning state is confirmed. Results show that compared with 16\|vehicle formation single\|deck EMU, reasonable vehicle layout scheme and marshalling form can increase the passenger capacity by 31.8% for double\|deck EMU; weight can be reduced by 2.4 t through effective control of the weight of other components; and diamond modal vibration frequency can reach 10.318 Hz when vehicle is in conditioning state.