The invention discloses a modified boron nitride nano-tube material and a preparation method thereof. According to the present invention, the modified boron nitride nano-tube material comprises component A-modified boron nitride nano-tubes and component B-modified boron nitride nano-tubes, activated boron nitride nano-tubes sequentially react with a trifunctional organic compound and is subjectedto a nucleophilic substitution reaction with polyethylene oxide to prepare the component A-modified boron nitride nano-tubes, activated boron nitride nano-tubes, an organic solvent N, a monomer compound, ethanol and distilled water are subjected to a reaction under the action of an initiator to prepare the component B-modified boron nitride nano-tubes, and a mass ratio of the component B-modifiedboron nitride nano-tubes to the component A-modified boron nitride nano-tubes is 0.3-0.6:1; and the prepared modified boron nitride nano-tube material can effectively achieve the synergistic toughening and reinforcing effect of each component material, is the high-performance toughening and reinforcing material, can be easily mixed with concrete, mortar and other components, and can be applied inthe fields of tunnel arch walls, viaduct bridge decks and other building materials.