Aiming at solving the problems of production process complexity, large equipment investment and high production cost during superfine iron powder preparation in the prior art, the invention provides a superfine iron powder preparation method and belongs to the field of powder metallurgy. The superfine iron powder preparation method includes: placing ferrous oxalate powder prepared from liquid-phase synthesis into a fluidized bed furnace and feeding gas in the weakly reducing atmosphere into the fluidized bed furnace, so that the ferrous oxalate powder is in fluidized movement in the fluidized bed furnace under the action of gas flow; heating the furnace to 350-500 DEG C, holding and reacting for 1-3 hours, so that superfine iron powder can be obtained. The superfine iron powder preparation method has the advantages that special hydrogen production equipment is unneeded, and the prepared superfine iron powder is more disperse, avoids aftertreatment processes such as crushing and is finer in granularity, larger in specific surface area, good in sphericity degree and more uniform in grain distribution.