Revegetation is regarded as a promising approach for large-scale remediation of bauxite residue in disposal areas. Formation of an aggregate structure and the dynamic processes of the organic pool are essential factors for achieving revegetation due to the high alkalinity, salinity and poor physical structure of the residues. The physical fractionation of organic carbon may identify specific organic carbon pools that are responsible for carbon management and control. Physical density fractionation facilitates the separation of soil organic carbon fractions and their associated mineral particles from different locations. Spontaneous vegetation encroachment upon bauxite residue at a disposal area in Central China, over a 20-year period, has revealed that natural soil-forming processes may convert the residues to a soil-like medium. Residue samples from three different stacking ages (1 year, 10 years and 20 years) were collected in order to determine the effects of natural soil-forming processes on aggregate formation and organic carbon fractions. The contents and distribution ratios of light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), particulate organic carbon (POC) and POC intra-residue aggregates were determined in this study. The results indicated that the content of organic carbon fractions in bauxite residue increased significantly under natural soil-forming processes. The proportion of LFOC of the total organic carbon was 0.36%-2.06%. With increasing stacking age, the distribution ratio of LFOC increased. Most organic carbon (97.24%-99.11%) was held in the HFOC, which indicated that organic carbon dynamics in the residues were controlled by the behavior of this fraction. In the HFOC, coarse POC and mineral-combined organic carbon predominated, whereas the distribution ratio of fine POC was relatively small. POC content was highest in 2-1 mm residue aggregates and lowest was in the 0.25-0.05 mm residue aggregate ranges in the three different stacking ages 1.21-1.85 g/kg (1 year), 2.62-2.95 g/kg (10 years), and 3.52-4.15 g/kg (20 years). Mean weight diameter was positively correlated with total organic carbon, LFOC, HFOC, and POC (r=0.908^**, 0.908^**, 0.889^**, 0.793^** respectively; P < 0.01). The content of free POC, occluded POC, and mineral-combined POC (Mineral:Mineral _{>0.05 mm} and Mineral _{<0.05 mm}) decreased with decrease in aggregate sizes. The order in a diminishing sequence for the distribution ratio of POC intra-residue aggregate size was 2-1 mm, 1-0.25 mm, <0.05 mm, and 0.25-0.05 mm. Among these, mineral-combined POC was the major fraction, and the proportion of free POC was the lowest. Natural soil-forming processes increased total organic carbon and fraction contents, and further enhanced the stability of organic carbon in bauxite residues, which was beneficial for organic carbon sequestration. The findings of this study may provide a theoretical basis for understanding carbon sequestration and contribute to improving the physical structure of bauxite residue.