A gas-liquid separator, wherein the gas-liquid separator comprises: a first cylinder, a second cylinder, a heat exchange pipe, a flow guide pipe, a distribution portion, and a lower sealing cover, wherein the first cylinder is located at an inner side of the second cylinder, the gas-liquid separator has a first chamber and a second chamber which are in communication with each other, the first chamber is located in the second cylinder and outside the first cylinder, the second chamber at least comprises a space located inside the first cylinder, the heat exchange pipe is located outside the first cylinder, and the heat exchange pipe is disposed in the first chamber; the distribution portion is fixed to the second cylinder, the distribution portion has a first passage, the flow guide pipe is fixed to the distribution portion, one end of the first passage is in communication with one end of the flow guide pipe, the other end of the flow guide pipe is in communication with the first chamber, the other end of the first passage is in communication with the first chamber; the lower sealing cover is fixed to the second cylinder, the lower sealing cover is located at the other side relatively away from the distribution portion, the gas-liquid separator further comprises a flow passage, at least part of the flow passage is located in the lower sealing cover, the flow passage is in communication with the first chamber, and the flow passage is in communication with the second chamber through the first chamber, characterized in that, the heat exchange pipe comprises a first collecting pipe, a second collecting pipe and a plurality of flat tubes (214, 215) arranged in parallel with each other, one end of the flat tubes (214, 215) is connected with the first collecting pipe, the other end of the flat tubes (214, 215) is connected with the second collecting pipe, and the first collecting pipe and the second collecting pipe are arranged approximately in parallel with each other. a first cylinder, a second cylinder, a heat exchange pipe, a flow guide pipe, a distribution portion, and a lower sealing cover, wherein the first cylinder is located at an inner side of the second cylinder, the gas-liquid separator has a first chamber and a second chamber which are in communication with each other, the first chamber is located in the second cylinder and outside the first cylinder, the second chamber at least comprises a space located inside the first cylinder, the heat exchange pipe is located outside the first cylinder, and the heat exchange pipe is disposed in the first chamber; the distribution portion is fixed to the second cylinder, the distribution portion has a first passage, the flow guide pipe is fixed to the distribution portion, one end of the first passage is in communication with one end of the flow guide pipe, the other end of the flow guide pipe is in communication with the first chamber, the other end of the first passage is in communication with the first chamber; the lower sealing cover is fixed to the second cylinder, the lower sealing cover is located at the other side relatively away from the distribution portion, the gas-liquid separator further comprises a flow passage, at least part of the flow passage is located in the lower sealing cover, the flow passage is in communication with the first chamber, and the flow passage is in communication with the second chamber through the first chamber, characterized in that, the heat exchange pipe comprises a first collecting pipe, a second collecting pipe and a plurality of flat tubes (214, 215) arranged in parallel with each other, one end of the flat tubes (214, 215) is connected with the first collecting pipe, the other end of the flat tubes (214, 215) is connected with the second collecting pipe, and the first collecting pipe and the second collecting pipe are arranged approximately in parallel with each other.