The invention provides a supercritical carbon dioxide compressor experiment circulating system which is mainly applied to experiment test of a supercritical carbon dioxide compressor. The system is characterized in that a closed circulating condition is supplied through a compressor testing unit; ladders, served to a compressor main engine shaft end of the compressor testing unit, of an injectingrecovering unit are sealed in a tooth staggering manner, so that gas leaked from the tail end of a mechanical seal can be subjected to single-stage/ two-stage injecting and then is recovered into maincurrent circulation; an SCO2 modulating unit is used for supplying a gas source to a circulating system, pressurizing and heating low-temperature liquid carbon dioxide and preparing a supercritical carbon dioxide working medium as a compressor experiment test working medium; a lubricating unit is used for supplying lubricating oil with proper parameters to a compressor main engine and related supporting devices in order to ensure that the compressor and a gear box bearing run normally; and a cooling unit is used for keeping heat balance of the whole circulating system in running. The system is applicable to supercritical working medium type high-pressure closed circulating experiment platform.