[Objective] Investigating the effects of herbaceous plant root systems at different restoration time points in open-pit waste dumps on soil aggregate stability and erosion resistance provides scientific basis for ecological restoration and soil and water conservation benefit assessment in mining areas. [Method] Tall fescue and alfalfa were selected as study subjects, with fallow grassland serving as the control. Using the LB method, the effects of simulated heavy rainfall erosion disturbance on two types of herbaceous plants with different restoration durations (1, 3, 5 years) and different depths (0-10, 10-20, 20-30 cm) were treated. The content of aggregates with diameter R>0.2mm (WR>0.2), mean weight diameter (MWD), mean geometric diameter (GMD), and soil erodibility factor K were measured. The soil aggregate composition and stability of alfalfa and tall fescue were analyzed, along with the relationship between root systems at different ages and soil layers and soil erodibility. The influencing factors were further investigated.[Results] ① The root area ratio (RAR) of 5-year-old alfalfa in the topsoil layer (0-10 cm) increased by 16.03 times compared to 1-year-old plants, while tall fescue increased by 5.6 times. Furthermore, the increase in root biomass density (RMD) of alfalfa in the deep soil layer (20-30cm) (16.56 times) was higher than that of tall fescue (5.5 times). ② Under the influence of two vegetation root systems, soil aggregate stability indices MWD and GMD in the rapid wetting (FW) disturbance mode generally showed the following order: 5a > 3a > 1a > fallow grassland. At different soil depths, the order was S3 (20-30 cm) > S2 (10-20 cm) > S1 (0-10 cm). Conversely, the soil erodibility factor K exhibited the opposite trend. ③ For the WR>0.2 indicator reflecting the proportion of large aggregates, the soil layer at a depth of 20-30cm showed a WR>0.2 increase of 25.46% and 7.93% after 5 years of alfalfa root growth compared to 1-year-old and 3-year-old plants, respectively. In contrast, the tall fescue root growth zone exhibited only a slight increase in the proportion of large aggregates within the 0-10 cm depth range.[Conclusion] For shallow soil layers near the slopes of waste dumps undergoing near-reconstruction, the soil aggregate stability indices within the growth zone of taproot-type alfalfa showed WR>0.2, MWD, and GMD showed significantly stronger correlations with RAR than those of fibrous-rooted tall fescue. Alfalfa roots promote the formation of large aggregates and enhance deep soil stability, while tall fescue reduces aggregate particle dispersion through dense surface fibrous roots that physically entangle, resulting in superior surface soil erosion resistance compared to alfalfa.