Abstract: A carbon nanomaterial functionalized needle tip is modified with a low work function material. The needle tip is formed by combining a carbon nanomaterial with a material of a needle tip through a covalent bond. The interior or outer surface of the carbon nanomaterial is modified with a low work function material. The material of the needle tip is a metal which can be any of tungsten, iron, cobalt, nickel, and titanium. The carbon nanomaterial can be carbon nanocone or carbon nanotube. The tip of the carbon nanomaterial has the same orientation as the metal needle tip. The low work function material can be selected from metals, metal carbides, metal oxides, borides, nitrides, and endohedral metallofullerene. The carbon nanomaterial functionalized needle tip has a lower electron emission barrier, and can effectively reduce the electric field intensity required for electron emission, and improve the emission current and emission efficiency.