Karst peak-cluster depressions are ecologically fragile, and slope runoff is a cause of severe soil erosions. However, the runoff-sediment pattern and influencing factors of typical lithologies slope erosion are still unclear. This study investigated the soil aggregate stability of limestone and dolomite and their effects on interrill erosion using rainfall tests. The dolomite soil aggregates were smooth with fine, tightly arranged particles. The limestone soil aggregates were rough with regularly shaped flocculent granular bodies. Soil aggregates of limestone had a higher microporosity than that of dolomite. The contents of macroaggregate with a particle size > 0.25 mm (WSA(0.25)) were significantly higher in limestone soils than in dolomite soils (P < 0.05). The mean weight diameter (MWD) trend was consistent with the WSA(0.25) value. The MWD value for forest soil of limestone was the highest among all soil types, 5.65 mm. With the Le Bissonais (LB) method, the MWD values followed the order of limestone > dolomite soils. The organic matter, Ca and Mg contents were highly significantly correlated with the aggregate stability (P < 0.01). During rainfall, the trend for soil runoff rates mainly indicated three stages: 0 similar to 10 min, rapidly increasing; 10 similar to 30 min, fluctuating; and 30 similar to 60 min, essentially stable. The stable runoff rates of limestone soils were lower than that of dolomite soils. At a slope of 10 degrees, the soil loss rate of dolomite forest was 0.16 g/(min center dot m(2)) higher than that of limestone. The sediment concentrations of dolomite soils were higher than those of limestone soils. The sediment aggregates were dominated by macroaggregates. The content of macroaggregates in dolomite soils ranged from 49.54% to 64.84% at 30 min of runoff and ranged from 51.60% to 69.88% in limestone soils. In general, limestone soils experienced less erosion than dolomite soils because of the difference in soil aggregate stability. The results of this study could provide a theoretical reference for karst rocky desertification management and ecological restoration.