The invention belongs to the field of air supply systems and particularly relates to an air supply system and method for an air source in a noise test room. According to the air supply system and method for the air source in the noise test room, the requirement for a large-flow air source is met, and the flow can be regulated. Sufficient liquid nitrogen is provided for the system in a double-impacting pressurization way, the temperature of vaporized nitrogen is increased to the temperature required by the system through an energy storage type vaporizer, an air distribution system is designed, and the pressure and flow of all branched pipelines can be regulated independently.