[Objective] Soil erosion is a critical factor constraining the sustainable development of both ecological environments and socio-economic systems. As a nationally designated key area for soil erosion control, the Dabie Mountains region has witnessed increasingly widespread conversion of forested land to orchards in recent years. This trend has further exacerbated soil erosion, leaving the region facing dual challenges of ecological fragility and impeded economic sustainability. To investigate the impact mechanisms of soil erosion in the Dabie Mountains and provide locally tailored scientific support for ecological management, [Methods] this study selected a tea oil plantation slope in the Dabie Mountains as the research site. An in-situ rainfall testing system was independently designed, simulating four rainfall scenarios: light rain, moderate rain, heavy rain, and heavy rain following prolonged drought. Tests were conducted under three vegetation coverage levels (20%, 40%, and 60%) to analyze changes in key parameters—soil moisture content, runoff volume, and sediment yield—and their interrelationships. [Results] Rainfall intensity emerged as the dominant driver of soil erosion on reforested slopes in the Dabie Mountains. When cumulative rainfall exceeded 42 mm and intensity reached 26 mm/h, vegetation"s protective threshold was breached, diminishing its buffering effect. The impact of vegetation coverage on erosion in the study area may exhibit diminishing returns. Under different rainfall conditions, increasing vegetation cover from 20% to 40% reduced average runoff by 31.33% and average sediment yield by 70.5%. When vegetation cover reached 60%, average runoff decreased by 38.80% and average sediment yield by 79.9%. Changes in the study area"s initial soil moisture content significantly influenced total soil erosion. When rainfall exceeded 42 mm and intensity reached 26 mm/h, a 5%–10% reduction in initial soil moisture content resulted in average decreases of 26% and 19% in runoff and sediment yield, respectively. [Conclusion] This study provides quantitative evidence for soil erosion prevention and control in the Dabie Mountains region.