A gas-liquid separation device, comprising: a cylinder, the cylinder defining a first cavity, a second cavity and a third cavity, the first cavity being in communication with the second cavity, the second cavity being in communication with the third cavity; an external port, the external port comprising a first port, a second port and a third port, the first port being in communication with the first cavity, the second port being in communication with the second cavity; an adapter, the adapter being at least partially disposed in the cylinder, the adapter defining a first channel and a second channel, a bottom end of the second channel and a bottom end of the first channel being both located in the third cavity, the bottom end of the second channel being lower than the bottom end of the first channel, the second channel being in communication with the first cavity and the third cavity; and a gas-liquid separation component, the gas-liquid separation component being located in the third cavity, and being configured to separate a gas-liquid two-phase refrigerant that enters the third cavity from the second cavity; wherein the gas-liquid separation device is configured to be operated in a first working state, wherein the first channel is configured to be closed so that the third port is not in communication with the third cavity; the first port serves as an inlet, and the second port serves as an outlet; wherein further the gas-liquid separation device is configured to be operated in a second working state, wherein the first channel is configured to be opened so that the third port is in communication with the third cavity; the second port serves as an inlet, the first port being in communication with the second channel serves as an outlet for a liquid-phase refrigerant after being separated from the gas-liquid two-phase refrigerant, and the third port being in communication with the first channel serves as an outlet of a gas-phase refrigerant after being separated from the gas-liquid two-phase refrigerant; characterized in that the third port is selectively in communication with or not in communication with the third cavity through the first channel by a switch; wherein the adapter comprises a first connecting pipe and a second connecting pipe, the second connecting pipe is partially received in and extends through the first connecting pipe, a cavity of the first connecting pipe at least partially forms the first channel, and a cavity of the second connecting pipe at least partially forms the second channel. a cylinder, the cylinder defining a first cavity, a second cavity and a third cavity, the first cavity being in communication with the second cavity, the second cavity being in communication with the third cavity; an external port, the external port comprising a first port, a second port and a third port, the first port being in communication with the first cavity, the second port being in communication with the second cavity; an adapter, the adapter being at least partially disposed in the cylinder, the adapter defining a first channel and a second channel, a bottom end of the second channel and a bottom end of the first channel being both located in the third cavity, the bottom end of the second channel being lower than the bottom end of the first channel, the second channel being in communication with the first cavity and the third cavity; and a gas-liquid separation component, the gas-liquid separation component being located in the third cavity, and being configured to separate a gas-liquid two-phase refrigerant that enters the third cavity from the second cavity; wherein the gas-liquid separation device is configured to be operated in a first working state, wherein the first channel is configured to be closed so that the third port is not in communication with the third cavity; the first port serves as an inlet, and the second port serves as an outlet; wherein further the gas-liquid separation device is configured to be operated in a second working state, wherein the first channel is configured to be opened so that the third port is in communication with the third cavity; the second port serves as an inlet, the first port being in communication with the second channel serves as an outlet for a liquid-phase refrigerant after being separated from the gas-liquid two-phase refrigerant, and the third port being in communication with the first channel serves as an outlet of a gas-phase refrigerant after being separated from the gas-liquid two-phase refrigerant; characterized in that the third port is selectively in communication with or not in communication with the third cavity through the first channel by a switch; wherein the adapter comprises a first connecting pipe and a second connecting pipe, the second connecting pipe is partially received in and extends through the first connecting pipe, a cavity of the first connecting pipe at least partially forms the first channel, and a cavity of the second connecting pipe at least partially forms the second channel.