The present disclosure relates to a method for making a carbon nanotube film. In the method, a bent flexible substrate having a curved surface and a pressing device are provided. A carbon nanotube array is formed on the curved surface. The bent flexible substrate is at least partially unbent, thereby at least partially unbending the carbon nanotube array. The unbent carbon nanotube array is pressed by the pressing device to slant the carbon nanotubes in the unbent carbon nanotube array, thereby forming the carbon nanotube film.