A method for manufacturing a carbon nanotube needle is provided. A carbon nanotube film comprising of a plurality of commonly aligned carbon nanotubes, a first electrode, and a second electrode are provided. The carbon nanotube film is fixed to the first electrode and the second electrode. An organic solvent is applied to treat the carbon nanotube film to form at least one carbon nanotube string. A voltage is applied to the carbon nanotube string until the carbon nanotube string snaps