Abstract: Project constructions significantly disrupt the surface and damage the original vegetation, potentially leading to soil erosion. Vegetation planting is one of the important means to restore the regional ecology disturbed by the subsequent implementation of the project. Based on field investigations, simulated rainfall experiments were conducted with bare slopes as controls to analyze the effects of Paspalum notatum Flugge (PF) on the runoff and sediment yielding characteristics and water-sediment benefits of engineering steep slopes (28°) under two vegetation densities (PF10:10 cm×10 cm, PF20:20 cm×20 cm). Results showed: ① The occurrence time of PF20 surface runoff under rainfall intensities of 1.0, 1.5 mm/min, and 2.0 mm/min was 61.81%, 0.88%, and 19.38% earlier than that of bare slopes. In contrast, PF10 delayed runoff occurrence when rainfall intensities of 1.5, 2.0 mm/min, with a lag benifits of 76.61% and 237.21%.② The average runoff rate on the bare slope under three different rainfall intensities was 3.23, 4.55 times, and 1.28 times than that of PF10. At rainfall intensities of 1.0 mm/min and 1.5 mm/min, the average runoff rate on the bare slope was 1.10 times and 1.27 times than that of PF20. However, at rainfall intensity of 2.0 mm/min, the average runoff rate of PF20 reached 1.08 times than that of bare slope. When rainfall intensity reached 2.0 mm/min, the average sediment yield rate of PF20 was 1.08 times than that of the bare slope. When rainfall intensity was 1.0 mm/min and 1.5 mm/min, vegetation significantly reduced erosion on steep slopes. In contrast, at 2.0 mm/min rainfall intensity, vegetation-induced erosion on steep slopes was greater than that on bare slope in the later stages of runoff. Overall, the average sediment yield on bare slopes was 7.83, 2.86, 1.24 times more than that of PF20 and 23.01, 6.98, 3.13 times more than that of PF10.③ The average sediment reduction benefits of PF20 and PF10 were 57.26% and 83.11%, respectively, while the average runoff reduction benefits were 7.08% and 56.22%, respectively. The runoff and sediment reduction benefits of PF10 were 7.94 and 1.45 times than those of PF20, respectively. Variance contribution rate analysis showed that rainfall intensity contributed 7.18 times and 4.31 times than that of the vegetation density to accumulation runoff and sediment production on engineering steep slopes, but vegetation density had a higher impact on regulating sediment production compared to runoff production. These research results can provide scientific guidance for the vegetation ecological restoration of engineering disturbed slopes.