A vacuuming sintering method for forming a carbon nanotube of a field display is disclosed. A cathode is attached to an anode, and the assembly of the cathode and anode is disposed on a heating element of a vacuum sintering furnace with cathode adjacent to the heating element. Each of the cathode and anode has at least one electrode lead connected to an external voltage source. The internal pressure of the vacuum sintering furnace is reduced, the heating element is activated, and a voltage is provided across the cathode and the anode, such that an electric field is generated between the cathode and the anode. The voltage is switched off after the electric field is formed and continuing heating for a predetermined period of time. The heating is terminated and the assembly of the cathode and anode is removed from the vacuum sintering furnace, such that the carbon nanotube is formed parallel to the electric field and perpendicular to the cathode, or one end of the carbon nanotube is inclined towards the anode to advantage electron generation therefrom.