The ice of transmission lines is mostly de-iced by DC de-icing method. After the current flow, the electromagnetic induction between the lines is considered to produce the electrodynamic effect, so as to study the de-icing of the ice-covered old lines. In this paper, the three-phase old single wire is taken as the research object, and the vibration equation of the old wire during the DC de-icing process is established. Through numerical simulation, the electrodynamic distribution of the three-phase single wire under different arrangement modes is investigated, and then the influence of the electrodynamic load distribution on the de-icing vibration of the old wire under different working conditions is analyzed. The results show that in the process of DC de-icing, the transverse electric power is the largest when the three-phase single wire is arranged horizontally, and the vertical electric power is the largest when the three-phase single wire is arranged triangularly. Considering the transverse vibration displacement of three-phase single wire under wind load, the electric force of the side phase under the horizontal arrangement has a great influence on the transverse vibration of the wire, and the difference rate of the displacement value reaches 7.37%. The electrodynamic force of the middle phase under the triangular arrangement suppresses the maximum vertical displacement of the conductor ice-shedding, and the electrodynamic force of the side phase increases the maximum jump height of the conductor ice-shedding. For three-phase single conductor with different ice thickness, the influence of electrodynamic force decreases with the increase of ice thickness, and decreases with the increase of de-icing rate of old conductor.