Abstract: Due to the "homomorphic replacement" of aluminum-iron, Al-goethite is formed, and it is difficult to achieve aluminum-iron separation. H₂ was used as the reducing agent, the typical high-iron gibbsite was pretreated by levitation magnetization roasting. The iron was enriched in red mud by Bayer dissolution and separation. The effects of roasting conditions on its phase structure, microscopic morphology, specific surface area and dissolution properties were investigated, and its magnetic changes before and after roasting were analyzed. The results show that the roasted ore is loose and porous, the specific surface area is greatly increased. The aluminum mineral is transformed into γ-Al₂O₃, the dissolution activity is good, and the hematite is transformed into magnetite, while the Al-goethite is transformed into a porous aluminum replacing magnetite structure. The aluminum element does not migrate, the separation effect of aluminum and iron is improved, the optimal roasting conditions are 500 ℃, the time is 10 min, the volume fraction of H₂ is 20%, the total gas flow rate is 500 mL/min, the relative dissolution rate of alumina reaches 96.47%, and the aluminum content in the dissolved red mud is reduced. The iron content is increased, the TFe content reaches 60.56%, which is 11.28 percent points higher than that of the original red mud. The iron mineral still maintaines the magnetite structure, and the saturated magnetization is 54.1 A·m²/kg. Further improvement of iron grade through magnetic separation is beneficial for achieving reduction of red mud.