The transcritical CO2 cycle mode has become one of the most popular research topics in the refrigeration field due to its advantages such as environmental friendliness, high-temperature heating performance, and adaptability to low environmental temperatures. This article discusses the thermodynamic principles and research progress of DMS technology for transcritical CO2 refrigeration heat pumps, providing reference for academic research and engineering applications. The research results indicate that the dedicated mechanical subcooling technology (DMS) for the transcritical CO2 cycle has broad development prospects in the field of refrigeration and heating. DMS technology can increase the COP of the transcritical CO2 cycle by more than 20%, and in some scenarios, it can already achieve the effect of replacing artificial synthetic refrigerants.