Abstract: At present, the running speed of Chinese high-speed Electric Multiple Units (EMUs) trains exceeds 350 km/h and the noise generated by the roof structure beneath the pantograph has become the largest noise source inside the carriage, affecting passengers' riding experience. The article adopts experimental data analysis and simulation methods to conduct experimental research on full path noise reduction optimization measures for the roof structure beneath the pantograph of CRH380B and CR400BF EMUs train, including optimization of damping treatment for roof profiles, control and structural optimization of sound radiation from roof interior panels, optimization of sound absorption/insulation materials for the combined structure of the roof, and optimization of sound transmission control for the full path structure of the roof structure. In consideration of the combination of the sound and vibration excitation from the pantograph and the bogie and based on the detailed characteristics of the optimized roof structure, the FE-SEA method is adopted to establish a noise characteristics simulation model of the entire vehicle compartment below the pantograph for quantitative evaluation of the improvement effects of noise reduction optimization measures of the roof structure on the noise inside the carriage. The simulation results show that the noise reduction optimization of the roof structure determined in this chapter reduces the noise inside the carriage below the pantograph of the CRH380B high-speed train by 3dB, and further reduces the noise of the CR400BF high-speed train by more than 1dB.