The present invention discloses a carbon nano-tube film composite material preparation method, which comprises: preparing a substrate; preparing a carbon nano-tube film; etching the carbon nano-tube film; placing the etched carbon nano-tube film on at least a surface of the substrate to form a carbon nano-tube structure so as to form a carbon nano-tube film composite material preform; and heating the carbon nano-tube film composite material preform to make the carbon nano-tube film structure and the substrate be compounded so as to obtain the carbon nano-tube film composite material. Compared with the method in the prior art, the method of the present invention has the following characteristics that: the carbon nano-tube film is etched before the carbon nano-tube film and the substrate are compounded to obtain the carbon nano-tube film with the partial thinned area or penetrating carbon nano-tube film so as to improve the interface performance of the carbon nano-tube composite material and reduce the interface defects, the obtained carbon nano-tube film composite material exhibits the excellent comprehensive performance and shows the application potential in a plurality of future fields.