Abstract: The flume scouring experiment indoors was conducted to study the runoff erosion characteristics in loess slope. Results showed that the sediment transportation ratio increased with the discharge of flow increased and changed in parabola form with the slope gradient. The sediment transportation ratio reaches the maximum value when slope gradient is between 21°and 24°. The flow shear stress had the same trend. Linear relationship existed between sediment transportation ratio and shear stress, and critical shear stress of the flow was 1.701 N/(m²·min), consequently the critical flow depth for the occurrence of rill erosion had inverse ratio with the sine value of slope gradient. In this experiment, the sediment mostly came from the middle and the top parts of the slope, while had little erosion in the below part of slope, which was only transported the sediment from the up-slope.