A powder feeding apparatus and a method of manufacturing a heat pipe are disclosed. The method includes: a) proving the powder feeding apparatus including a vibrating tray and a pump (800); b) positioning a tube in the vibrating tray; c) inserting a mandrel (400) into the tube from a first open end of the tube, wherein at least one groove (410) is defined in an end of the mandrel corresponding to a second open end of the tube; d) positioning a feeder (300) on the first end of the tube; e) driving the vibrating tray to vibrate and feeding powder into the tube from the feeder whilst the pump is operating to generate a forced airflow flowing from the first to the second open end of the tube. By using this method, bridging of the powder is prevented.