The liquid lead-bismuth eutectic (LBE) is the coolant of the heat exchanger in China initiative Accelerator Driven System, which may have a risk of structural failure due to the washout of the coolant in the inlet of the heat exchanger. It is necessary to study the mechanical properties of the heat exchanger bundles of CiADS, especially the fatigue life of the bundle structure in the transverse flow of the LBE. The numerical simulation is the Lattice Boltzmann method combined with the large eddy simulation by Python codes. The velocity distribution of the flow field and the time domain characteristics of the heat exchanger bundles’ force are calculated, and the frequency domain characteristics of the heat exchanger bundles’ vibration are obtained by Fourier transform. The bundles vibrate at high cycle fatigue in turbulent flow at high Reynolds number. The transverse flow of LBE does not affect the fatigue life of the bundle. No structural failure occurs in the CiADS heat exchanger due to the transverse flow of LBE.