The utility model relates to an air conditioning system, including the main line, the main line is including the compressor, cross valve, outdoor heat exchanger, first orifice union and the indoor heat exchanger that connect into the return circuit, air conditioning system still includes the subsidiary pipeline of being established ties in proper order by electronic expansion valve, liquid storage pot, check valve and second orifice union, assist the pipeline connect in parallel in in the main line outdoor heat exchanger the export with pipeline between the indoor heat exchanger inlet, be equipped with pressure sensor in air conditioning system's the main line, be used for monitoring air conditioning system pressure. The utility model discloses an air conditioning system has realized storing the refrigerant when high temperature, refrigerant logging in circulation again during low temperature, and system's operation is stable, and lowering system operating load does benefit to the environmental protection, and has improved user experience.