The invention discloses a novel air supply and enthalpy increasing system and a control method thereof. A frequency converter module of the system is arranged between an air supply electromagnetic valve and a compressor air supply opening, the frequency converter module is provided with a frequency converter module temperature detection device, and a frequency converter module heat exchange device is arranged at the bottom of the frequency converter module. Flash evaporation refrigerating fluid in a flash-tank enters the frequency converter module heat exchange device through the air supply electromagnetic valve, the frequency converter module heat exchange device exchanges heat with the frequency converter module, and accordingly the temperature of the frequency converter module is lowered. The frequency converter module temperature detection device is connected with a master controller. The master controller is connected with the air supply electromagnetic valve, a first electronic expansion valve arranged between the flash-tank and an indoor heat exchanger, and a second electronic expansion valve arranged between the flash-tank and an outdoor heat exchanger. The invention further provides the control method of the system. The problems that according to an existing air supply and enthalpy increasing technology, under a hostile working condition, namely an ultralow temperature or superhigh temperature working condition, the temperature of the frequency converter module is excessively high, so that the stability of the frequency converter module and even the entire air supply and enthalpy increasing system gets worse, and the service life is shortened can be solved.