Iron-gallium (Galfenol) alloys are new classes of magnetostrictive material which have moderate strain under very low magnetic field intensity, low hysteresis, and high tensile strength. These unique mechanical properties and superior magnetic attributes motivate the use of Galfenol in various actuation and sensing applications. Galfenol systems are usually operated in dynamic magnetic field environment, in which the influence of dynamic loss cannot be neglected. When Galfenol is applied to dynamic magnetic field, the power losses are separated into hysteresis loss, classical eddy current loss and anomalous (or excess) loss. Based on static energy-averaged hysteresis model of Galfenol, the dynamic hysteresis strain and magnetization model considering eddy current losses and excess losses of ferromagnetic material under dynamic magnetic field was proposed. Static strain and magnetic field were measured using testing system of Galfenol magnetic properties. The results showed that the calculation results were in good agreements with experimental results. Relationships between strain and dynamic magnetic field under different frequencies of 〈100〉 oriented polycrystalline Fe83Ga17 were measured. The frequencies were 1Hz, 10Hz, 20Hz, 40Hz, 60Hz, 100Hz, 200Hz and 300Hz. The results of experiments and calculation agreed well when frequencies were below 200Hz, and when frequencies were higher than 200Hz, the results of experiments and calculation had deviations. The model can be used in dynamic application of Galfenol alloy under low frequency such as actuators and vibrators.