The sloping fields of red soil are the main source of agricultural production in south China. A specific soil parent material, red soil helps decrease erosion resistance. Furthermore, the combination of population increase and reduction of cropland increases soil erosion significantly, which significantly restricts the region's socio-economic development and ecological environment construction. Soil aggregates are the basic unit of soil structure, and their formation and stabilization have a direct impact on runoff and the loss of red soil in sloping farmland. The formation and stabilization of soil aggregates is a natural process influenced significantly by soil properties, soil organic carbon (SOC) in particular. Hedgerow and straw mulching, which are listed as important factors affecting the soil organic carbon and aggregate content by increasing the input of soil organic matter and improving soil water-stable aggregate (WSA) stability, are considered reasonable methods of restoring and reconstructing the fertility of eroded soil in red slope farmland. Compared to mulching, a hedgerow is a vegetative barrier preferably placed along a topographical contour perpendicular to the direction of water flow in the field, in order to trap sediments and reduce runoff velocity. The effect of trapping sediments and reducing runoff varies depending on the distance of the soil from the hedgerow. Most preliminary studies have focused on the effect of either hedgerow installation or mulching on soil and water conservation, soil nutrient condition, non-point pollution, composition and fractal features of soil micro-aggregates. Very few studies have investigated the effect of both hedgerows and mulching on the soil water stable aggregate size distribution and aggregate-associated organic carbon, especially the WSA distribution characteristics on the slope.Based on field soil and water conservation experiments we designed and carried out beginning in 2009, hedges of Vetiver Grass (H), rice straw mulching (M), and hedges of Vetiver Grass+rice straw mulching (HM) were applied to sampling plots to investigate the effect of biological metrics of water and soil conservation on soil water-stable aggregate stability (WSA) and aggregate-associated organic carbon content. Additionally, this study reports the area of influence of hedges on the soil structure and soil organic carbon, using Vetiver Grass hedges as an example. The soil was sampled at 0 m, 2 m, and 4 m uphill of the hedge. The results indicate that, compared to conventional cultivation (CK), the organic carbon content in the H, M, and HM treatments increased by 0.07-2.42 g/kg. The effect of Vetiver Grass on WSA size distribution and aggregate-associated organic carbon decreases gradually as the distance from hedge increases. H treatment increases the macro-aggregate (> 2 mm) content and the aggregate-associated organic carbon, whereas M treatment increases the micro-aggregate (< 0.25 mm) content. Overall, HM treatment is the best in terms of improving slope red soil structure. These results indicated a significant positive correlation between soil organic carbon and the organic carbon content of the macro-aggregates (>0.25 mm) in the soil. These results will play an important role in establishing reasonable measures of soil and water conservation measurement and determining good method of facilitating carbon accumulation in red slope farmland of southern China.