The vibration of power lines in rainy environments was researched using the concentric cylindrical gap to which D.C. voltage was applied. Consequently, it has been solidly conformed that the vibration of power lines begins at threshold voltage of corona, and that the amplitude of the vibration increases as the numbers of falling water drop per unit time increase. The vibration phenomen take place in straight line, elliptic or circular motion as voltage is applied the numbers of vibration nearay accord with the elastic vibrarion theory.