The aggregates of slightly eroded red soil and severely eroded red soil derived from Quaternary red clay were used to understand the stability and the breakdown mechanisms by applying wetting sieving method and Le Bissonnais method, and the relationship between aggregate stability and some soil properties, such as different forms of Fe oxides and Al oxides,organic matters,CEC and clay content were also studied. The results of the study indicated that: the aggregates of severely eroded soils were more stable than those of the slightly eroded soils; The slaking of entrapped air in aggregate destroyed the aggregate severely, especially for the slightly eroded soils. Meanwhile mechanical breakdown and micro-cracking did little on the aggregates. The aggregate stability positively related with the percentage of Fe_d, Al_d, Fe_o and clay content, but negatively related to the SOC, which may because the low organic matters in the severely eroded soils and the effect of cultivation.