A method for making a high-density carbon nanotube array includes the steps of: (a) providing a substrate having a carbon nanotube array formed thereon; (b) providing an elastic film; (c) stretching the elastic film uniformly, and covering the elastic film to the carbon nanotube array; (d) exerting a pressure uniformly on the elastic film, and shrinking the carbon nanotube array and the elastic film under the pressure; and (e) separating the nanotube array from the elastic film to acquire a high-density carbon nanotube array.