Abstract: As an important technical means of urban rail transit vehicle intelligent operation, smart HVAC (heating, ventilation and air-conditioning) technology mainly adjusts the AC (air-conditioner) operation mode according to the vehicle operating environment data to improve ride comfort, conducts real-time monitoring of AC units operation status and fault prediction and early-warning of key components, so as to realize intelligent health management and improve the operation-maintenance efficiency of AC units is improved. Smart HVAC system is established by combining vehicle AC, vehicle on-board network and PHM (prognostics health management) ground support system, setting sensors to monitor the environment data and adaptively adjust the AC operation status to improve the interior air quality. In terms of PHM (prognostics and health management), the safe operation of AC units is guaranteed by building a diagnostic model, collecting and transmitting AC unit operation data, timely warning frequent faults of AC units in time, predicting the service life of the aging key components and taking corresponding health management measures. For vehicle maintenance, with different diagnostic and prediction model data, the smart HVAC technology formulates reasonable maintenance process for AC units and develops the conventional maintenance mode, turning fault repair and timing repair into an intelligent ′state repair′ mode based on safety monitoring and health management.