A method for controlling a heating throttling element in a multi-split air conditioning system, the multi-split air conditioning system comprising an outdoor unit, a shunt device and a plurality of indoor units, the plurality of indoor units including a heating indoor unit and a refrigerating indoor unit, the outdoor unit including a compressor, and the shunt device including a gas-liquid separator, a first heat exchanger, a second heat exchanger, a first throttling element, a heating throttling element, a high pressure pressure sensor, and an intermediate pressure sensor, an outlet of a first heat exchange flow path of the first heat exchanger being in communication with an inlet of the first throttling element, an outlet of the first throttling element being in communication with an inlet of a first heat exchange flow path of the second heat exchanger, an outlet of a second heat exchange flow path of the second heat exchanger being in communication with an inlet of a second heat exchange flow path of the first heat exchanger, the heating throttling element being disposed between the outlet of the first heat exchange flow path of the second heat exchanger and the inlet of the second heat exchange flow path of the second heat exchanger, an inlet of the gas-liquid separator is connected to an outlet of the outdoor unit, a liquid outlet of the gas-liquid separator is in communication with the inlet of the first heat exchange flow path of the first heat exchanger, and a vapor outlet of the gas-liquid separator is in communication with an inlet of the heating indoor unit, an outlet of the heating indoor unit is in communication with the inlet of the first heat exchange flow path of the second heat exchanger, the outlet of the first heat exchange flow path of the second heat exchanger is in communication with an inlet of the refrigerating indoor unit, an outlet of the refrigerating indoor unit and an outlet of the second heat exchange flow path of the first heat exchanger are in communication with an inlet of the outdoor unit, the high pressure sensor is disposed at the outlet of the first heat exchange flow path of the first heat exchanger, and the intermediate pressure sensor is disposed at the inlet of the first heat exchange flow path of the second heat exchanger, the method comprising:: obtaining a target exhaust pressure of the compressor or a saturation temperature (Tc) corresponding to the target exhaust pressure;: controlling the compressor based on the target exhaust pressure or the saturation temperature (Tc) corresponding to the target exhaust pressure to make the compressor operate stably, obtaining the high pressure and the intermediate pressure of the shunt device after the compressor operates stably, and calculating a pressure difference between the high pressure and the intermediate pressure, and characterised by: obtaining a target pressure difference between the high pressure and the intermediate pressure of the shunt device, and adjusting an opening of the heating throttling element based on the pressure difference and the target pressure difference.: obtaining a target exhaust pressure of the compressor or a saturation temperature (Tc) corresponding to the target exhaust pressure;: controlling the compressor based on the target exhaust pressure or the saturation temperature (Tc) corresponding to the target exhaust pressure to make the compressor operate stably, obtaining the high pressure and the intermediate pressure of the shunt device after the compressor operates stably, and calculating a pressure difference between the high pressure and the intermediate pressure, and characterised by: obtaining a target pressure difference between the high pressure and the intermediate pressure of the shunt device, and adjusting an opening of the heating throttling element based on the pressure difference and the target pressure difference.