The distribution of combined humus in soil aggregates of particle size ranging from >4, 2–4, 1–2, 0.5–1 and 0.25–0.5 mm in three eroded (according to its vegetation, slope and soil thickness divided into slightly, moderately and severely erosion) Ultisols in subtropical regions of China and its relationship with the average percentage of >0.25 mm water-stable aggregates (WSA) were investigated by using wet-sieving method. Results showed that the carbon contents in three kinds of combined humus (tightly, loosely and steadily) decreased with erosion aggravating. In the slightly eroded soil, the carbon content of tightly and loosely combined humus in aggregates increased with increasing particle size, while the carbon content of steady combined humus decreased. In moderately and severely eroded soil, the carbon contents in the three kinds of combined humus were close in different size aggregates. The carbon content of three kinds of combined humus showed highly significant positive correlation with the percentage of > 0.25 mm water-stable aggregates in soil of different erosion degrees (r = 0.88 and 0.74). This showed that the different blinding modes and tightness of minerals and humus had different effects on eroded soil structures.