The importance of plant root systems in reducing soil erosion is well established; however, existing evaluation approaches based on individual root traits often do not adequately represent the complexity of root-soil interactions. To develop a comprehensive parameter that reflects the effects of plant root systems on soil erosion processes, eight representative herbaceous species from different successional stages were selected from the Chinese Loess Plateau. Root morphology, biomass, mechanical strength, and architectural characteristics were considered, and these parameters were integrated to construct a comprehensive root system parameter using the Amoeba chart method. Relative soil detachment capacity was measured through overland flow scouring experiments under six shear stress levels. The results showed that the comprehensive root system parameter, derived from root surface area density, root mass density, root cohesion, and topology index, ranged from 0.28 to 1.72 among the eight species. The maximum value was observed in Bothriochloa ischaemum (Linn.) Keng, while the minimum values occurred in Artemisia capillaris Thunb. and Astragalus adsurgens Pall. With vegetation succession, the comprehensive root system parameter increased. The mean value for plants with fibrous root systems was 1.41 times that of plants with tap root systems. Relative soil detachment capacity varied significantly among the eight species, ranging from 0.012 to 0.107 kg m-2 s-1, and showed a decreasing trend with vegetation succession. Relative soil detachment capacity was 14% lower in herbaceous plants with fibrous root systems than in those with tap root systems, indicating their stronger ability to reduce soil detachment. The effects of plant root systems on soil erosion differed among species and root types, and these differences were effectively captured by the comprehensive root system parameter. Relative soil detachment capacity decreased exponentially with increasing values of the comprehensive root system parameter. This study demonstrates that integrating multiple root characteristics can improve the prediction of soil erosion for typical grassland species in the studied ecosystems. However, the applicability of the proposed parameter to other vegetation types and ecosystems remains to be tested and will require substantially more data across a wider range of species and environmental conditions.