The invention discloses a method for purifying iron powder from coarse-particles of steel-smelting sludge, and relates to the method for effectively reclaiming and re-using the coarse-particles of the steel-smelting sludge in iron and steel industry. Aiming at a problem at present that metallic iron in the coarse-particles of the steel-smelting sludge isn't utilized effectively, the invention provides the method for purifying the iron powder from the coarse-particles of the steel-smelting sludge, which comprises steps of selecting magnetically, ball-grinding, sorting through gravity, drying, screen-classifying, reducing finely, bruising, combining and the like. The iron powder with MFe>=90% and TFe>=96% is separated successfully from the steel-smelting sludge through the invention, the iron power with TFe>=98% which can be used for welding rods and the like can be obtained, the utilizing value of the coarse-particles of steel-smelting sludge of rotary stoves can be increased greatly, the utilizing fields of the coarse-particles of steel-smelting sludge of rotary stoves can be developed, and according to industrial experiments and productions, the method is certified to be the method for producing the iron powder with little investment, short technological process, low cost and good benefits, and thereby the invention is beneficial to be extended and applied.