Rainfall erosion process can be divided into-different aspects,runoff washing and raindro pimpact,but their contribution to soil erosion can not be determined accurately under the condition of conventional rainfall simulation with single runoff plot.Relationships between rainfall erosion and runoff erosion and their contribution to soil erosion have been researched by using rainfall simulation with dual runoff plots.The research results show that under the same slope gradient and rainfall intensity,the sediment delivery in down-slope caused by runoff water from up-slope will increase with the increase of runoff water from up-slope.Under the condition of same slope steepness and runoff,sediment delivery caused by rainfall erosion is bigger than that caused by feeding runoff washing.Sediment delivery has increased by 50% when rainfall intensity increases 1 time. Sediment production caused by raindrop impact takes up 27.2%～45.8% of total rainfall erosion,contribution from raindrop impact to sediment production is affected by rainfall intensity and erosion pattern.