A given field emission element includes a carbon nanotube field emission wire and at least one supporting protective layer coating an outer surface of the carbon nanotube field emission wire. The carbon nanotube field emission wire is selected from a group consisting of a carbon nanotube yarn, a wire-shaped CNT-polymer composite, and a wire-shaped CNT-glass composite. A method for manufacturing the described field emission element includes the steps of: (a) providing one carbon nanotube field emission wire; (b) forming one supporting protective layer on an outer surface of the carbon nanotube field emission wire; and (c) cutting the carbon nanotube field emission wire to a predetermined length and treating the carbon nanotube emission wire to form the field emission element.