Numerical simulation of dynamic response of the vortex fan case in the unsteady flow is carried out. With the experiment of vibration and noise of vortex fan in the fuel cell vehicle, the fan dynamic response in the unsteady flow excitation is calculated, and the numerical simulation results show that the vortex fan resonance is occurred which results in noise radiation because of its lower inherent frequency consistent with fan exciting frequency, and the method can accurately simulate the dynamic response of the internal flow excitation.