Through artificially simulated rainfall experiments, we studied the regularities of the runoff and sediment yield on slopes of different gradients (5°,and 10°) under different rainfall intensities (30 mm/h, 60 mm/h, and 90 mm/h) with different coverages (60% coverage of Festuca arundinacea grassland in the first year of planting, and bare land). A quantitative study was carried out on the soil and water regulation of F. arundinacea grassland. The results showed that: (1) Festuca arundinacea grassland had a remarkable effect on extending the initial runoff time. However, such effect decreased with the increase of rainfall intensity and slope gradient. The effect on the extension the initial runoff time of grassland was not significant under rainfall intensity of 90 mm/h on the 10° slope. (2) Under different experimental conditions, there were significant differences between F. arundinacea grassland and bare land, except under rainfall intensity of 90 mm/h on the 10° slope. (3) Under different experimental conditions, the total runoff of F. arundinacea grassland was about 0.8 times as much as that of the bare land, and the total sediment yield of F. arundinacea grassland was 1/244.68-1/28.34 times as much as that of the bare land. (4) A 60% coverage of F. arundinacea grassland could effectively reduce runoff and soil erosion, but the reduction degree was different. When the rainfall intensity was 30 mm/h, 60 mm/h, and 90 mm/h, the average runoff reduction was 33.23%, 23.04%, and 13.78%, respectively. The sediment reduction could be more than 95% under different rainfall conditions. (5) Sediment-carrying capacity of F. arundinacea grassland was different from that of the bare land under the same test conditions. The amount of soil erosion in the F. arundinacea grassland was lower than that of the bare land under the same runoff conditions. (6) The relation between runoff and sediment was established for F. arundinacea grassland and bare land.