Abstract: Understanding the sorting and transport of sediment particles during erosion is essential for clarifying the erosion mechanism of spoil tips and for developing effective soil and water conservation measures. In order to investigate the response of sediment particle sorting and transport to hydrodynamic parameters during the erosion process of spoil tips, two representative spoil materials, namely Lou soil and aeolian sandy soil, were selected as research objects. Runoff scouring experiments were carried out under two slope (28°and 32°) and four inflow rates (8, 12, 16, and 20 L/min). Based on these experiments, the particle-size distribution characteristics of eroded sediment, the sorting features of sediment particles, and the corresponding transport mechanisms under different soil types were systematically analyzed. In addition, the relationships between sediment particle characteristics and hydrodynamic parameters were examined to identify the key controlling factors of sediment sorting and transport in the erosion process of spoil tips.The results showed that the eroded sediment from both Lou soil and aeolian sandy soil spoil tips was dominated by the 0.002～<0.050 mm size fraction, which accounted for more than 46% of the total sediment. However, the response patterns of sediment particle composition to slope and inflow rate differed between the two soil types. For the aeolian sandy soil spoil tips, the particle-size composition of eroded sediment was more sensitive to slope, indicating that slope played a more important role in controlling the detachment and transport of sediment particles. By contrast, for the Lou soil spoil tips, the transport of coarse particles in the 0.250～2.000 mm size fraction was mainly controlled by inflow rate, and the interaction between slope and inflow rate had a significant effect. These results demonstrate that the influence of hydraulic conditions on sediment transport is strongly dependent on soil type and particle composition. Compared with the Lou soil spoil tips, the eroded sediment from the aeolian sandy soil spoil tips had a larger mean weight diameter, ranging from 0.061 to 0.085 mm, and a smaller fractal dimension, ranging from 2.494 to 2.561. This finding indicates that coarse particles in aeolian sandy soil were more easily detached and transported during runoff scouring, and that the sediment sorting process was relatively weak. In contrast, the smaller mean weight diameter and larger fractal dimension of the eroded sediment from Lou soil suggest a relatively stronger sorting effect and a greater enrichment of fine particles in the transported sediment. Therefore, the differences in soil texture and particle composition between Lou soil and aeolian sandy soil lead to distinct sorting responses during the erosion process of spoil tips. Among the tested hydrodynamic parameters, stream power was identified as the optimal predictor of the sorting characteristics of eroded sediment from the aeolian sandy soil spoil tips. Specifically, stream power showed the strongest relationship with mean weight diameter and fractal dimension(R²= 0.92 and 0.55, respectively). For the Lou soil spoil tips, runoff shear stress was the optimal hydrodynamic parameter for characterizing sediment sorting (R²= 0.80 and 0.31, respectively). The contribution of suspension-saltation exceeded 61% for the aeolian sandy soil spoil tips and 83% for the Lou soil spoil tips, indicating that most of the eroded sediment was transported in the form of suspended and saltating particles rather than as bed load. Moreover, based on stream power, the relative contributions of suspension-saltation and bed load in the eroded sediment from Lou soil and aeolian sandy soil spoil tips could be quantitatively described by power and logarithmic functions. This result suggests that stream power can serve as an effective hydraulic indicator for quantifying the partitioning of different transport modes during the erosion process.These findings not only deepen the fundamental understanding of the dynamic erosion mechanisms of spoil tips but also provide a solid theoretical basis for designing and optimizing targeted, differentiated soil and water conservation measures based on specific regional soil types.