Abstract: A design method for a supercritical carbon dioxide compressor includes: obtaining a performance curve of the supercritical carbon dioxide compressor based on the fluid similarity theory; performing off-design performance correction of the supercritical carbon dioxide compressor based on the performance curve; controlling a dry gas seal temperature of the supercritical carbon dioxide compressor based on a correspondence between temperature and pressure; and providing a fluid dynamic pressure gap between a high-speed shaft gear and a low-speed shaft gear in a gearbox of the supercritical carbon dioxide compressor, and adjusting a gearbox thrust through the fluid dynamic pressure gap.