The solution is analyzed for periodic vibration of magnetostrictive actuator excited by harmonic alternating current. The total energy of kinetic, strain and magnetic energy stored in the rod is expressed as a functional of displacement variable. By using perturbation approach, the problem is changed into three perturbation problems. This paper presents the second perturbation solution to the periodic vibration problem for a magnetostrictive rod with the strong engineering background of the Terfenol-D actuator. The solution has very high accuracy.