A method of preparing a carbon nanotube/polymer composite material is provided. The method includes (a) providing a carbon nanotube-based film and a pre-polymer solution; (b) placing the carbon nanotube-based film at a bottom of a container, and pouring the pre-polymer solution in the container; and (c) polymerizing the pre-polymer solution and simultaneously integrating the pre-polymer solution with the carbon nanotube-based film. As such, a carbon nanotube/polymer composite material, including the polymer-impregnated nanotube layer and an upper polymer layer, is obtained. A multi-layer composite can be produced by essentially repeating this process, using the upper polymer layer as the base layer for the formation of the next layer set thereon.