A method for manufacturing a refrigerant guide tube of a heat exchanger and a refrigerant guide tube manufactured using the method and a heat exchanger with the refrigerant guide tube are disclosed. The refrigerant guide tube includes tube body and channels extending through a wall of the tube body. The tube body is formed by a butt joint of side edges of more than one bar-shaped plate materials along the length direction. The method allows forming the refrigerant channels of the guide tube before or during forming the tube body when the method is used to manufacture the guide tube, so as to avoid directly forming the channels on the tube body and make the process of manufacture the guide tube simpler and more convenient.