A cooling coolant pipe of a server cabinet includes multiple tube bodies interconnected in series and at least one adjustable valve. In each of the tube bodies a first chamber and a second chamber that are adjacent to and separated from each other, the second chambers of the two adjacent tube bodies are in communication with each other, and a wall surface of each of the tube bodies has at least one connection port in communication with the first chamber. The adjustable valve is disposed in one of the tube bodies. The first chamber in each of the tube bodies is in communication with the second chamber in the tube body through the adjustable valve. In this way, the adjustable valve adjusts the flow rate of a cooling fluid flowing from the second chamber to the first chamber.