The arsenic sandstone area with extremely severe hydraulic erosion was selected as the research object. Based on continuous monitoring experiments of runoff plots in the field, 3D laser scanning, UAV aerial photography and variance-mean ratio method were used to compare and analyze the characteristics of flow and sand production and the evolution of slope microtopography under three typical natural vegetation patterns (aggregated distribution, uniform distribution and random distribution) on arsenic sandstone slopes. The results showed that: (1) The uniform distribution pattern had the most obvious effect on mitigating soil erosion on arsenic sandstone slopes under hydraulic erosion conditions, with a flow reduction rate of 64%, a sand reduction rate of 72%, and the lowest soil loss of 0.05 kg/m² compared was bare slopes. There was a polynomial curve relationship between runoff and sediment volume, and its fitting function was y=-0.0462X²+0.5355X-0.865, R²=0.736. (2) The erosion area of the uniform distribution pattern was the smallest, which was 12.28 m², and the deposition area was the largest, which was 3.44 m², and the soil erosion intensity was weaker than other slopes, mainly light erosion. (3) The correlation between runoff sediment volume and average deposition depth of uniform distribution pattern was strong, with a significantly positively correlated with runoff volume (p<0.05), and the correlation coefficient was 0.603, and had a highly significant positive correlation with sediment volume (p<0.01), and the correlation coefficient was 0.771.