There are also many forms of gradient magnetic field design and production. The use of electromagnet gradient poles can generate a radially asymmetric magnetic field. It is usually used in tests that require unidirectional force on the sample, such as force magnetometers and magnetic powder samples. Screening, etc.; it can also be used as a multi-pole electromagnet to generate a uniform gradient magnetic field in the radial direction of the magnetic field. For the design of gradient magnetic field coil applied to gradient magnetic field, it can realize one-dimensional, two-dimensional and three-dimensional gradient magnetic field. The usual practice is to connect the two coaxial coils in series and reverse to set the optimal coil spacing.