The invention relates to a low temperature heat pump air conditioning system, consisting of a compressor, an electromagnetic four-way valve, an outdoor heat exchanger, a throttle mechanism, a super cooling intercooler, an indoor heat exchanger and a gas-liquid separator. In the invention, an air supply device for the super cooling intercooler is provided, when heating is carried out under the low temperature working condition, the super cooling intercooler is used for supplementing the compressor with medium pressured saturated refrigerant gas to increase the super cooling degree of the refrigerant in the main circulation and simultaneously increase inspiration capacity of the compressor so as to enhance the mass flux of the refrigerant in the main circulation, thus heating capacity is increased and compression ratio and gas discharge temperature are decreased. The low temperature heat pump air conditioning system has the advantages of simple structure, easy manufacturing, low manufacturing cost, high efficiency, energy-saving, stable and reliable operation, etc.