In order to study the effects of hedgerow width on runoff and sediment yield process of purple soil slope and explore the critical hedgerow width for effective control of soil erosion, three hedgerow with different width (20, 30, 40 cm) were set up to analyze the runoff and sediment yield of purple soil slope land under different rainfall intensities (30, 60, 90 mm/h). The results showed that:(1) Hedgerow could effectively delay runoff generation time on purple soil slope, and the relationship between the runoff yield and the hedgerow width could be fitted into a quadratic equation (R²=0.99). With the increase of hedgerow width, the flow rate decreased, and the flow rate inside the hedgerow decreased most obviously, and the fluctuation range of the flow rate curve decreased. (2) Hedgerow could effectively restrain the increase of sediment yield on the slope in the early stage of sediment yield process, and the sediment yield on the slope decreased with the increase of hedgerow width. When the rainfall intensity was 30 mm/h and 90 mm/h, the R² of quadratic equation between the sediment yield and the hedgerow width was 0.99. (3) The hedgerow width caused an extremely significant effect on runoff and sediment yield. Under 30 mm/h rainfall intensity, the hedgerow with a width of 30 cm could achieve a remarkable benefit of reducing runoff and sediment yield.