A powder feeding apparatus of manufacturing a heat pipe includes a vibration tray having a supporting board and a plurality of pipes positioned in the supporting board of the tray. A mandrel is coaxially inserted in each of the pipes. A feeder is located corresponding to an end of each pipe for feeding powder into the pipe. A vibration source drive the tray to vibrate along a direction perpendicular to an axial direction of each of the pipes when feeding the powder into the pipes from the feeders, whereby the pipes vibrate with substantially the same amplitude in the vibration direction.