Superconducting magnet will not lose energy when it runs under the condition of direct current, and a huge magnetic field can be generated by strong current. In addition, it has stable magnetism, high uniformity of magnetic field in space, small volume and light weight, so it is widely used. It has important practical functions and great application prospects in the fields of electrician, transportation, medical care, military industry and scientific experiments, and some of them have achieved practical benefits. For example, magnetic resonance imaging equipment using superconducting magnets has become one of the most popular clinical diagnostic equipment in hospitals, and thousands of magnetic resonance imaging equipment have been used in hospitals all over the world. In addition, scientific instruments such as superconducting nuclear magnetic resonance spectrometer have also become commodities and have been widely used.