A method for forming a carbon nanotube film is provided. An elastic substitute substrate and a carbon nanotube array transferred on a surface of the elastic substitute substrate are used. The carbon nanotube array is configured for drawing a carbon nanotube film therefrom. The carbon nanotube film has carbon nanotubes joined end to end. The elastic substitute substrate is stretched along a plurality of directions to increase lengths of the carbon nanotube array along the plurality of directions. The carbon nanotube film is drawn from the stretching carbon nanotube array.