Giant Magnetostrictive Actuator (GMA) is a new type of vibration control driving device. However, due to its complicated internal magnetic circuit, the working performance of the actuator is seriously affected by the size and uniformity of the magnetic induction intensity. In order to solve the above problems, based on the theory of linear magnetostriction and electromagnetics under static conditions, a finite element model of the GMA was established using the finite element software ANSYS, and the influence of the material parameters of the excitation coil, the magnet and the inner wall of the magnet on the magnetic induction intensity was studied. At the same time, the size and uniformity of the magnetic induction intensity at the axial centerline of the giant magnetostrictive rod are used as the evaluation criteria, Parameters such as the opening and closing magnetic circuit, the axial length of the excitation coil, the magnetic permeability of the material, the air gap, and the radius of the magnetizer are optimized. The results show that when the closed magnetic circuit is adopted, the magnitude and uniformity of the magnetic induction intensity are greatly improved; after the optimization of the magnetic circuit, the magnitude of the magnetic induction intensity is increased by 0.1T, and the uniformity is increased by 10.27%.