The process of erosion sediment yield of slope-gully system in Loess Plateau was studied by using slope-gully system physical model and runoff scouring method,integrating rare-earth element tracing technology.The results indicate that erosion rate of slope-gully system in the slope is bigger than it in the gully,that is to say,slope erosion is more serious than gully erosion.In the range of experimental flow discharges,there is a critical discharge.Erosion rate is increased with the flow increasing when the flow is less than the critical value.Erosion rate is decreased with the flow increasing when the flow is greater than the critical value.And the critical value is 12 L/min.Erosion rate is fluctuated with the scouring duration when the flow is uniform.Initiation erosion rate is increased and the time that erosion rate achieved the maximum is shorter with the flow increasing.Initiation erosion rate is increased and the time that erosion rate achieved the maximum is shorter with the flow increasing.