the present invention provides a method for producing nano - sized fe powder having a polymer coated layer on a surface thereof , so as to prevent the nano - sized fe powder from being oxidized under atmosphere . the method includes : gasifying an iron pentacarbonyl 5 ) or an iron acetate 2 fe ) precursor in a ceramic bubbler ; forming nano - sized fe particles due to the crystallization of fe gas while mixing the gasified precursor with ar gas in a reactor ; and precipitating the nano - sized fe particles in a polymer solution in a chamber , before the nano - sized fe particles are oxidized . according to this technique , fe powder on the order of tens of nms in size , and having a polymer coated layer , are obtained from the fe precursor . a system for producing the nano - sized fe powder is also disclosed .