The cryogenic system maintains the low temperature environment necessary for the superconducting magnet to be in the superconducting state. The cooling method of superconducting magnet is generally immersion, that is, the superconducting magnet is directly placed in the cryogenic liquid. For low temperature superconducting magnets, liquid helium (4.2K) is used at low temperature. For large superconducting magnets, in order to improve cooling capacity and efficiency, superfluid helium can be used for cooling, and the cryogenic system also needs to adopt a closed cycle to set refrigerant to recover the evaporated cryogenic liquid. The high-temperature superconducting magnet based on Bi system can achieve a magnetic field strength of 3~5T after cooling only 20~30K, and the high-temperature superconducting magnet based on Y system can achieve a certain magnetic field strength even at 77K. With the progress of technology, the use of high-power chillers to directly cool superconducting magnets can become a practical solution, but the current level of technology, it is difficult to achieve the cooling of large superconducting magnets.