The invention discloses a high-temperature superconducting low-temperature helium self-circulation cooling system. Vertical temperature and density differences of low-temperature helium in the system allow natural convective circulation to form, and the problems that the superconducting magnet used in the direct cooling manner of a small refrigerator is poor in cooling effect and the necessary application of expensive low-temperature helium pumps in forced convective circulation cooling causes high cost are solved. After the system stabilizes, operating pressure is low; the safety problem is solved. A superconducting magnet and a current lead form a whole which can be lifted in or out of magnet mounting space and which is convenient to demount, mount and change; cooling medium helium has controllable temperature, and conditions for the study on performances of high-temperature superconducting magnets at specific temperature are provided.