Gradient magnetic fields are designed and manufactured in various forms. The gradient pole heads of electromagnets can generate magnetic fields with radial asymmetry of magnetic fields. They are usually used in tests requiring single-direction stress of samples, such as force magnetometers and magnetic powder sample screening. It can also be used as a multipolar electromagnet to generate a uniform gradient magnetic field in the radial direction of the magnetic field. The radial section of the magnetic field is zero at the center, and the field area where the magnetic field increases uniformly from the center to the periphery is a standard circle. This kind of magnet is designed for gradient magnetic field coils to be applied to gradient magnetic fields and can realize one-dimensional, two-dimensional and three-dimensional gradient magnetic fields. The common practice is to connect two coaxial coils in series and in reverse to set the best coil spacing.