A gas-liquid separation apparatus includes a container and a separating pipe located in the container. The container includes an annular wall and two lids covering two ends of the wall. The container has a cavity surrounded by the wall and the two lids. An inlet extends through one lid and an outlet extends through the other lid. The separating pipe is disposed in the cavity of the container and in communication with the inlet and the outlet of the container. A plurality of apertures is defined in a body of the separating pipe and in communication with a space inside the separating pipe and the cavity of the container. The liquid with gas dissolved therein enters into the separating pipe via the inlet of the container. The liquid is degassed by the separating pipe. The de-gassed liquid exits the separating pipe via the outlet of the container.