Provided are a boron-nitride nanoplatelet(s) (BNNP)/metal nanocomposite powder and a preparing method thereof, the BNNP/metal nanocomposite powder including a base metal and BNNP dispersed in the base metal and configured to serve as a reinforcement of the base metal, wherein the BNNP are interposed between metal particles of the base metal in the form of a thin film of a plurality of layers and combined with the metal particles, and an amount of the BNNP in the base metal is greater than 0 vol % and less than 90 vol %.