Abstract: A multipurpose system of cooling and heating supply and firefighting servo-control based on energy-storage CO2 circulation and an operating method thereof are provided, the system based on the CO2 compression refrigeration circulation with three-stage compression and multi-stage energy storage, provides three-levels standing cool volume for the cool end, domestic hot water and heating for the hot end, and extinguishing agents CO2 for the firefighting end. By means of a new modular process design, the system realizes the independent operation and free combination of refrigeration circulation in multi-stages, so as to achieve the purpose of adjustable working conditions, flexible output and high efficiency of energy utilization. The multi-stage energy storage of liquid CO2 can realize the “flexibility” of system power consumption, and acts as a standing safety module for firefighting to be put into the safe operation of the energy system.