The invention discloses a gas-liquid separator, an air-conditioning system and a control method. The gas-liquid separator comprises a shell and an oil return component, wherein the oil return component comprises a driving device, and the driving device is used for driving liquid oil in the shell to flow into a compressor connected with the gas-liquid separator. The gas-liquid separator is provided with the oil return component used for oil return and the driving device is arranged on the oil return component, driving force is provided by the driving device to allow the liquid oil in the gas-liquid separator to flow into the compressor, so that the requirement for oil return can be met even when oil return amount is large, and then the operation reliability of the compressor adopting the gas-liquid separator is improved.