Six plots of simulated speedway slope with different gradients are studied.Soil and vegetation measures are made to study the mechanism and characteristics of rill development on simulated slopes under rainfall and flow scouring.The results show small rills develop on sandstone slopes planted with lawn of much cover during the final term of rainfall.However。rills develop obviously and with complex shape on loess and gravel slopes planted with shrubs.The maximum width and depth of rill is 18.4 and 16.5 cm respectively.The combination of engineering measures and vegetation measures is the best choice to protect speedway slopes.