Abstract: To realize the magnetization of hydrogel mixed with NdFeB powder, a new type of magnetic field generator based on Helmholtz coil is designed in this paper. The 3D model of the magnetic field system is drawn using the Maxwell software 3D module, and the Magnetostatic static magnetic field solver is used to analyze the influence of the added auxiliary coil distance on the field strength, and the optimized structure of the magnetic field generator is obtained; then compare the magnetic field generator and Helm The central magnetic field intensity and magnetic induction line distribution density of the Holtz coil verify the reliability of structural optimization. The results show that when the auxiliary coil distance is 70 mm, the central magnetic field strength is the largest; when the number of ampere turns is the same, the central magnetic field strength of the magnetic field generator is significantly higher than that of the Helmholtz coil, and the final optimized magnetic field generator′s central magnetic field strength can be reaching 1.37 T, the distribution of magnetic lines of induction is more uniform and denser. The simulation results can provide a reference for the structural design and working characteristics analysis of the magnetic field generating device and shorten the design cost and development cycle of the magnetic field generating device.