The invention discloses a high-heat-conduction graphene nanometer composite material and a preparation method thereof. The preparation method comprises the following steps of combining liquid crystals and graphene through physical and chemical effects to obtain liquid crystal-graphene; filling the liquid crystal-graphene into a polymer base body material to obtain a liquid crystal-graphene/polymer composite material. The graphene is subjected to functional modification; the liquid crystal functional graphene is filled into a polymer base body so as to improve the dispersion performance of the graphene in the base body and the compatibility with the base body; the heat conduction performance of the base body material is improved; in addition, a certain shearing force field or electromagnetic field is exerted on the liquid crystal-graphene/polymer composite material before the solidification, so that the sequencing of the graphene in the field-induced effect is regular; the liquid crystal induced graphene orientation is ordered; the anisotropic trends are shown, so that the more excellent heat transfer properties are achieved; finally, the liquid crystal-graphene/polymer composite material with the excellent heat conduction performance is obtained.