Abstract: Metro station ventilation and air conditioning system that accounts for the most energy consumption and carbon emission is selected as the research objective to determine the calculation method of its carbon emission and explore the carbon emission characteristics. In this paper, a carbon emission calculation model for metro station ventilation and air conditioning system based on the life cycle theory is established, it calculates the life cycle carbon emissions of typical station ventilation and air conditioning system according to the calculation model and engineering example parameters. The results show that the CO2 emission intensity of the case station is significantly higher than that of ordinary buildings, and CO2 emission of the annual unit refrigerating capacity is 917.39 kg/(kW·year); the operation stage accounts for the largest proportion in the life cycle, reaching 97.87%; and the 39.42% emission of cold source water system accounts for the largest proportion among all subsystems.