In this research, using the energy approach, a generalized dynamic model is derived for Galfenol (Iron-Gallium Alloy) based on the mechanical strain theory and the Jiles-Atherton model. Experiments have been conducted to measure the relationship between the strain and the magnetic field. Using experimental data, unknown parameters in the model have been identified by a developed optimization algorithm. Results show that the novel dynamic model with identified parameters is capable of describing the performance of the Galfenol rod. Simulation and experiment dynamic responses of Galfenol rods are derived. The simulation and the experiment both agree that the magnitude of the strain output decreases with the increase of the excitation frequency.