Abstract: In order to analyze the mechanism of aeolian vibrations of transmission lines and the wind energy power input, a numerical simulation method has been studied based on the computational fluid dynamics (CFD). The aeolian vibration of transmission lines has been simplified to a two-dimensional cylinder surrounded by unsteady wind flow. Firstly, the Karman’s vortex street behind the static transmission line has been calculated in the subcritical crosswise wind field. Through compared with the classical literature the model has been proven valid. Then the influence of the oscillation amplitude to the Karman’s vortex has been analyzed using the oscillating transmission line model. Based on these researches, the relationship between the oscillation amplitude and wind energy power input has been obtained. By comparing with the curve obtained from a series of wind tunnel experiments, the mechanism of aeolian vibrations and their self-limit characteristic has been confirmed. In addition, the serviceability of the different wind energy power input curves has been studied.