Vibration analysis of a supersonic mixed compression intake is carried out under periodic back pressure by using one-way fluid structure interaction method.Steady flow and transient flow in the intake are simulated with finite volume method.The total pressure recovery and the exit flow distortion of the steady flow solution are very close to Anderson and Wongs experiment results.The frequency components of pressure transferring to the intake cowl wall are analyzed using FFT method for the unsteady flow,and are compared with the natural frequencies of the intake structure to avoid the resonance of the intake structure.The dynamic response of the intake structure is simulated with finite element method considering geometric nonlinearity.The displacement history of structure is obtained,and the region with large amplitude of vibration is identified.It indicates that the forced vibration occurs in the intake under the excitation of the oscillating back pressure.The static displacement is two times of the cowl wall thickness,while the peak value of the dynamic displacement is 10% of the cowl wall thickness.