In order to study the influence mechanism of fluctuating pressure on the interior noise of the high-speed train, the pressure value of the external wall of a train was extracted by the method of combining the wavelet threshold de-noising and the correlation coefficient, and the value of the fluctuating pressure was obtained. The finite element method was used to establish the structure, flow field and the coupling model of flow- induced vibration. The modal frequency of the coupled system was analyzed, and the fluctuating pressure was loaded to the coupling model, and the displacement of the body structure and the change of the internal pressure of high-speed train were analyzed. The results showed that the vibration displacement at the window was the largest, and the vibration displacement of the body structure was related to the inherent characteristics of the body structure and the spectrum characteristics of the loading pressure. The internal pressure level of high-speed train was mainly concentrated in the middle and low frequency section below 100 Hz. The internal pressure on both sides of the body was larger than that in the middle part of the body. The pressure near the wall of the body was more susceptible to the modal influence of the body structure. The internal pressure level of high-speed train and the modal frequency of the coupling system were related to the vibration displacement characteristics of the body.