Abstract: Based on the Maxwell’s equation， the inner magnetic field radial distribution model of giant magnetostrictive actuator was built by combining with piezomagnetic equations， in which the permittivity， compressive prestress of the material were introduced. The theoretical analysis and numerical simulation of the model were done， and the influences of the material characteristic parameters on the material inner magnetic field and hysteresis characteristics were discussed. The results showed that the inner magnetic field radial distribution of giant magnetostrictive material (GMM) has obvious skin effect and hysteresis characteristics. Under the effects of conductivity and permittivity， the phenomenon of dualpeak is found in magnetic field distribution of GMM. Along with the radius direction of GMM， the hysteresis characteristics between excitation magnetic field and inner magnetic field gradually become weak， and the magnetic loss decreases. The skin effect of GMM decreases with the increase of compressive prestress.

Key words: giant magnetostrictive actuator, permittivity, dualpeak, inner magnetic field, skin effect, hysteresis