The invention discloses a metal alloy powder preparing device, and relates to the technical field of additive manufacturing or powder metallurgy. The device comprises an air suction smelting chamber,a powder making chamber, a powder temporary storage chamber and a secondary smashing nodulizing chamber which are arranged from top to bottom. Under the high pressure active atmosphere environment, high-temperature metal alloy is melted, the melting point and the interface tension are reduced, and fluidity of metal alloy melt is improved; through the high pressure active atmosphere environment, high-pressure jetting is triggered, and through centrifugal spray, the metal alloy powder is prepared; through primary radio frequency plasma heating, under the active element precipitation power effect, the high-temperature metal alloy powder is broken again, finally, through secondary radio frequency plasma heating, broken powder is melted and spherized, and meanwhile, active elements are removed.The method has the advantages of being high in yield, uniform in powder particle component, high in sphericity degree, small in particle size and good in fluidity.