Abstract:[Objective] Iron oxides are sensitive to the pedogenic environment and an important cement of soil aggregates. The differentiation of iron oxide phases occurs at multiple scales in natural systems, which may affect the formation and stability of soil aggregates. This study aimed to explore the differentiation of iron phases, including total iron (Fet), free Fe-oxide (Fed), amorphous Fe-oxide (Feo), hematite (Hm), and goethite (Gt) at the hillslope, profile and aggregate scales and evaluate their effects on the stability of soil aggregates.[Method] A topo-sequence of Ferrisol, derived from granite in the hilly area of central Fujian Province, was fractionated into aggregates using wet-sieving and pipette methods. Fed and Feo in bulk soils and different aggregates were extracted with the citrate-bicarbonate-dithionite (CBD) solution and the acid ammonium oxalate (AAO) solution, respectively. Diffuse reflectance spectroscopy (DRS) was applied to determine Hm and Gt content. The percentage of water-stable aggregate (WSA) and the mean weight diameter (MWD) were evaluated.[Result] At the hillslope scale, the Fed and Fed/Fet in bulk soils decreased, while the Feo and Feo/Fed increased downslope. Meanwhile, the Hm and Hm/(Hm+Gt) significantly declined, while the Gt kept a little variation downslope. At the profile scale, the upper layers generally possessed higher contents of Fed and Gt, as well as lower levels of Feo and Hm in contrast to the deeper layers. At the aggregate scale, Fed, Feo and Gt were enriched in micro-aggregates. The contents of Hm were comparable in the micro- and macro-aggregates, while Hm/(Hm+Gt) increased with the aggregate size. Micro-aggregates were the main components, but the >0.25 mm macro-aggregates dominated the aggregate stability along the hillslope. The WSA of 0.5~0.25 mm and 1~0.5 mm aggregates were significantly positively correlated with Feo and Feo/Fed respectively, and the WSA of 2~1 mm macro-aggregate was significantly positively correlated with the Hm and Hm/(Hm+Gt).[Conclusion] The iron oxides demonstrated significant differentiation from hillslope scale to aggregate scale. The soil aggregate stability in the top-slope and bottom-slope profiles were higher than those in the transitional profiles due to the upslope enrichment of Hm and downslope enrichment of Feo along the hillslope.