Abstract: The aim of this study was to investigate the characteristics of grass root distribution and its effects on soil anti-erodibility in purple soil areas. Two grass species, Vetiveria zizanioides and Digitaria sanguinalis, growing on slopelands were chosen as the experimental materials. Root and soil samples were taken from 0-10, 10-20, and 20-30 cm soil depths. Root parameters, soil shear strength, and anti-scourability of the root-soil system were measured to explore the relationship between root distribution and soil anti-erodibility. The values of overall root parameters and diameter parameters (root length density, root surface area density, root volume density, and root weight density) were higher for V. zizanioides roots than for D. sanguinalis roots in 0-30 cm soils. Compared with D. sanguinalis roots, V. zizanioides roots were more conducive to reducing soil bulk density, improving soil microaggregate composition, and increasing the soil organic carbon content. Soil shear strength and anti-scourability of the root-soil systems were highest in 0-10 cm soils and lowest in 20-30 cm soils. The values of both parameters were higher for V. zizanioides than for D. sanguinalis. A correlation analysis indicated that 1.0<d (diameter)≤2.0 mm was the critical diameter class affecting cohesion and the anti-scourability index, followed by d≤1.0 mm. The results of this study provide a theoretical basis for vegetation management strategies to conserve soil and water in purple soil areas.