Abstract: Red mud and coal gangue contain a large amount of aluminum, which can be used as a substitute of bauxite. The mixture of red mud and coal gangue with the addition of sodium carbonate and calcium carbonate were calcinated in high-temperature, resulting in the insoluble alumina and silicon dioxide in the minerals transformed into soluble sodium aluminate and insoluble calcium silicate respectively, through activating red mud and coal gangue by alkali in red mud, sodium carbonate and calcium carbonate. Furthermore, the aluminum was extracted by alkali leaching from the calcined product. The optimum calcination parameters was a temperature of 1250 ℃, a calcination time of 45 min, a Na₂O/(Al₂O₃+Fe₂O₃) molar ratio of 1.1∶1, and CaO/SiO₂ molar ratio of 2∶1, and the leaching rate of aluminum reached 78.45% with a higher conversion rate of alumina in red mud and coal gangue. The process takes advantage of the residual alkali in red mud and significantly reduces the dosage of reagents such as sodium carbonate, thereby reducing production costs and environmental pollution.