The invention relates to a nanocomposite aluminum particle for aluminothermic reduction reaction and a preparation method thereof. Metal aluminum, mischmetal lanthanum, cerium, praseodymium, neodymiumand metal additives are added to a vacuum melting furnace so as to be smelted, and after smelting is completed, molten liquid is poured into a mold and is processed into material blocks; metal aluminum ingots are added to a medium-frequency induction furnace, after the metal aluminum ingots are heated and molten, the processed material blocks are added, and full mutual fusion is realized under the action of electromagnetic stirring; and a preparation device of the nanocomposite aluminum particle for the aluminothermic reduction reaction is adopted to inject into a centrifugal rolling and rotating mixing drum through a tundish, the centrifugal rolling and rotating mixing drum is driven to rotate by the rotation of a high-speed variable frequency motor, and an aluminum solution forms the nanocomposite aluminum particle in the centrifugal rolling and rotating mixing drum. The preparation method has the advantages of simple process and reasonable proportion; the aluminum particle providedby the invention has the advantages of high heat effect per unit mass, low apparent activation energy, high reduction speed, easiness in slag-metal separation and the like in the aluminothermic reduction reaction, and the one-time finished rate of products is high.