Aiming at the serious problem of soil erosion on the Loess Plateau,combined with the current situation of water shortage in the region,under the condition of limited vegetation measures,the convex slope was taken as the research object,and the grass belt was laid on 5 different positions on the upslope,and the indoor water discharge was used. The experiment studied the slope erosion process and sediment particle size fractionation characteristics under different vegetation spatial positions,and clarified that the vegetation can effectively exert the soil and water conservation effect,and primitively proposed the optimal position of soil and water conservation effects under low vegetation coverage. The results showed that: (1) The Cv value of the flow intensity of different vegetation spatial positions is between 10.26% and 15.50%,and the fluctuation of the runoff intensity is small. The runoff intensity of position A and the runoff of position B and position F were small. The intensity showed a significant difference (p<0.05),and the Cv value of the sediment yield in different vegetation spatial positions were above 26.00%. The sediment yield intensity of the position A showed significant difference with sediment yield of other positions (p<0.05). The effect of laying grass strips on the slope on the sediment production process was greater than the impact on the runoff process. (2) After planting vegetation on the upslope of the convex slope,the total runoff yield was reduced to a different extent compared with the bare slope (Position A),and the water reduction benefit of the position F was 19.65%. The sediment yield reduction benefit of position B was as high as 70% or more. (3) The average value of the average weight diameter (MWD) of sediment particles in different vegetation spatial position was: Position A > Position F > Position D > Position E > Position C > Substrate > Position B,the mean value of MWD gradually stabilized and approached the substrate with the prolongation of runoff generation time. Under the condition of hydraulic erosion with vegetation coverage,the erosion particles were mainly fine grains,the content of powder grains was higher,and the content of sand was relatively small. The farther the vegetation was from the top of the slope,the easier it was to erode 0.002~0.05 mm of powder. This study will help to deepen the understanding of the spatial distribution of vegetation on the mechanism of convex slope erosion and sediment production.