The invention discloses a method for preparing iron powder through red mud suspension roasting, and belongs to the technical field of mineral processing. The method comprises following steps: firstly,red mud is subject to fine grinding and then subject to one-segment weak magnetic separation; secondly, one-segment weak magnetic separation tailings is subject to strong magnetic separation, and one-segment weak magnetic concentrate and strong magnetic concentrate are mixed to serve as preconcentration concentrate; thirdly, the preconcentration concentrate is placed in an oxidizing roaster, gasand air are led, and the preconcentration concentrate is subject to oxide roasting to obtain oxide powder ore; fourthly, the oxide powder ore is placed in a reduction roaster, nitrogen and reduction gas are led, and reduction roasting is carried out; fifthly, the roasted ore is subject to fine grinding, and then, second-segment weak magnetic separation is carried out. The method is simple in process flow, the equipment treatment amount is large, the product character is easily controlled, industrial application is achieved, the method is energy-saving and environment-friendly, and enlargementis easily achieved.