The invention relates to a method for preparing a carbon nanotube composite material. The method comprises the following steps of: providing a carbon nanotube structure, wherein the carbon nanotube structure comprises a plurality of carbon nanotubes; providing reaction solution, and immersing the carbon nanotube structure in the reaction solution, wherein at least one metal compound is dissolved in the reaction solution; and performing thermal treatment on the carbon nanotube structure immersed with the reaction solution in an anaerobic atmosphere to ensure that the metal compound in the reaction solution performs decomposition reaction. The carbon nanotube composite material prepared by the method has high tensile strength and Young modulus.