The invention discloses a method for preparing a gamma'-Fe4N soft magnetic material by utilizing
liquid nitrogen via high-speed ball milling, and belongs to the field of soft magnetic materials. According to the method, high-energy low-temperature
grinding in the
liquid nitrogen is utilized to obtain a nano material FexN with a
nitrogen atom
supersaturation degree; and at low temperature, the material is crispy and the surface volume ratio is very high, so that 22% of
nitrogen atoms are adsorbed on the surface of a sample; after the temperature is up to 300 DEG C, annealing is carried out to ensure that alpha-Fe directly undergoes
phase change to be converted to gamma'-Fe4N, so as to prepare a
nanocrystal gamma'-Fe4N soft magnetic material. The method is simple to convenient to operate, low in cost and suitable for large-scale industrial production, and is a novel
replacement method for preparing high-level soft magnetic materials with ideal
magnetism. The gamma'-Fe4N soft magnetic material prepared by the method has the advantages of being high in Ms, low in coercive force and
high surface resistivity, and can be applied to
transformer and inductors operated in high-frequency semi-conductor switches.