In recent years, as the production of alumina in China has sharply increased, the available high-quality bauxite resources have fallen short for alumina in China. Meanwhile, the amount of low-grade bauxite resources, i.e., containing high-sulfur and carbon, with a low aluminum-to-silicon ratio, is underused due to the lack of available technology. The depletion of high-quality bauxite resources and the utilization problem of low-grade bauxite ores have become the main bottlenecks restricting the sustainable development of the alumina industry in China. Therefore, the effective utilization of low-grade bauxite resources is of great significance for the sustainable development of the alumina industry in China. To solve this issue, the present study employed a potential process of sodium nitrate pre-roasting activation coupled with leaching in low-alkali solution for low-grade bauxite. The bauxite and pre-roasted clinker were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), etc. The effects of technical parameters such as the temperature of pre-roasting bauxite alkali leaching, leaching time, and solid-liquid ratio on the leaching of alumina were studied in detail, focusing on the mechanism and kinetics of low-alkali leaching of pre-roasted bauxite. The results showed that after pre-roasting with sodium nitrate, the microstructure of the bauxite became loose, exhibiting a porous and grooved structure. Under the appropriate leaching conditions with a solid-to-liquid ratio of 300 g/L, using a lower concentration of caustic soda solution 160 g (Na2O)/L compared to the traditional Bayer process for 60 minutes at 270℃, 87.22% alumina of the pre-roasted bauxite with an original aluminum-to-silicon ratio of 3.57 was leached, and the aluminum-to-silicon ratio of red mud reduced to 0.88. This method could effectively improve the leaching rate of alumina in the bauxite and overcome the limitation of the theoretical leaching rate of Bayer process. The apparent activation energy for the leaching of alumina in the pre-roasted bauxite was regressed as 23.21 kJ/mol, the leaching process was controlled by mixed mechanisms.