Abstract: With the rapid development of superconducting technology, more and more attention has been paid to the refrigeration system that provides cryogenic environment for superconducting materials. This paper introduces a sub -cooled nitrogen cooling system for HTS motor based on the principle of decompression and cooling. It includes the technical specifications and related requirements, the overall structure, key technologies, thermal load analysis and calculation, etc. The system adopts vacuum cooling to obtain sub-cooled liquid nitrogen and coil wires in the cooling motors. Liquid nitrogen inlet and outlet temperatures are 68K and 72K, respectively. The utility model is mainly composed of a liquid supply dewar, a sub-cooled box, an evacuation pump, a superconducting coil dewar, a reflux dewar, a low temperature pipeline and a temperature meter. The experiment indicates that the cooling system is reasonable in design and easy to operate, and the loading operation of the superconducting motor is successfully realized.

Key words: decompression cooling, superconducting motor, sub-cooled liquid nitrogen, coil dewar