Heat transfer enhancement is achieved by flow-induced vibration in planar elastic tube bundle heat exchangers. The optimum of structural parameters of tube bundle is of importance to the characteristic and control of flow-induced vibration. The influence of pipe structural parameters such as cross section diameter, thickness and connectors mass on vibration characteristic is studied in this paper with numerical simulation method. Based on the amplitude of flow-induced vibration and stress intensity, the characteristic of planar vibration and vertical vibration are compared, and the amplitude range of infinite fatigue life is predicted. The results show that the cross section diameter of pipe and the connectors mass have major influence on the vibration characteristic of tube bundle. Compare to the planar vibration of tube bundle, the vertical vibration has much advantage in the vibration amplitude and stress intensity distribution.