The invention discloses a method for preparing a modified carbon nanotube and methyl methacrylate composite material by a thermo-compression method, comprising the following steps of: firstly adding an oxidizer to carbon nanotubes, stirring, centrifugally separating, washing and drying so as to obtain modified carbon nanotubes; secondly adding the carbon nanotubes to MMA (Methyl Methacrylate) in batches, adding an initiator and a dispersing agent,stirring and heating to 80-100 DEG C, keeping the temperature, and putting the products into molds hot pressing and cooling to obtain the composite material. In the method, the modified carbon nanotubes have hydroxyl groups or carbonyl groups and then are polymerized with the monomer MMA to prepare the composite material by the thermo-compressionmethod; the modified carbon nanotube not only has better imbibition property with the organic MMA, but also can be controlled to form more stable chemical bonds in PMMA (Polymethyl Methacrylate); in addition, when the thermo-compression is carried out under the certain temperature and pressure, the mechanical property of the products cam be enhanced, and the tension force can be more than 45MPa.