In this study, the interior noise of the next generation high-speed train (HST) is analysed by using the statistical energy analysis (SEA) method. Exterior sound level data are used as input and for the sound transmission loss of each panel, intensity transmission loss is measured based on ASTM E2249-02. For the interior acoustic property, reverberation time of the passenger compartment is measured. Finally, interior noise level is measured in a running train at 350㎞/h in order to verify the validity of the simulation result.