A gas-liquid separator includes a first cylinder, a second cylinder, a heat exchange pipe, a flow guide pipe, a distribution portion, and a lower sealing cover. The gas-liquid separator has a first cavity and a second cavity. The second cavity includes at least the space located in the first cylinder. The distribution portion includes a first passage. One end of the first passage is communicated with that of the flow guide pipe. The other end of the flow guide pipe is communicated with the second cavity. The other end of the first passage is communicated with the first cavity. The lower sealing cover is located at the other side far away from the distribution portion. The gas-liquid separator further includes a flow passage located, at least in part, in the lower sealing cover, communicated with the first cavity and communicated with the second cavity.