Slope gradient is an important factor affecting the surface slope erosion of red soil. The objectives of this study were to investigate the impact of slope gradients on runoff and sediment yield erosion processes. Three rainfall intensities (1.0 mm/min, 1.5 mm/min, 2.0 mm/min) and three slope angles ( 10°, 15°, 20° ) were comparatively studied under simulated rainfall. Results showed that: (1) Under the same rainfall intensity, the time of the initial runoff were shortened with the increasing slope gradients on red soil, slope angle and runoff volume were positively correlated; under the same slope gradient, both the time of initial runoff and runoff volume decreased with the increasing rainfall intensity. (2) The effects of slope gradients on the sediment yieldwere more complicated, an increasing slope gradient generally increased the average sediment yield, which had greater volatility under 15°. (3) The contribution of slope gradients to runoff volume was more than 60%, and to sediment yield was above 30%. These findings provided theoretical basis for erosion prediction and prevention in erosion area of red soil.