【Objective】 Based on the current situation and severity of soil and water loss, it is vital to investigate the nature and extent of surface structure degradation of slope farmland and long-duration rainfall characteristics in the red soil region of southern China.【Method】 The method of long-term rainfall simulation were adopted to test the effects of topsoil structure and rainfall intensity on rainfall redistribution, runoff and sediment yield. In this paper, three rainfall intensities, 30 mm·h^-1, 60 mm·h^-1 and 90 mm·h^-1, respectively, and three cultivation depths, 10 cm, 20 cm and 30 cm, respectively, were set to study the effects of tillage lager depth and rainfall intensity on surface flow, subsurface flow, soil loss rate and erosion pattern.【Result】 The results showed that:(1) The topsoil structure significantly changed the redistribution process of runoff. Higher tillage layer depth can mitigate the effects of rainfall intensity, reduce the surface flow coefficient, and increase subsurface flow. Under the condition of 60 mm·h^-1 and 90 mm·h^-1 rainfall intensity, the average surface flow coefficient decreased in the sequence of 70.5% (TLD10 cm), 62.9% (TLD20 cm), and 56.8% (TLD30 cm), and the average subsurface flow ratio increased in the sequence of 7.1% (TLD10 cm), 12.3% (TLD20 cm), and 18.1% (TLD30 cm). (2) The soil loss rate was enhanced with the increase in rainfall intensity but decreased with the depth of the tillage layer. Under 60 mm·h^-1 rainfall intensity, the peak soil loss rate of 10 cm, 20 cm and 30 cm tillage depth were 35.1, 25.6 and 20.5 g·m^-2 min^-1, respectively. For 90 mm·h^-1 rainfall intensity, these values were 68.7, 55.8 and 48.4 g·m^-2 min^-1, respectively. (3) Rainfall intensity and topsoil structure significantly affect the final slope erosion forms. With the increase of tillage layer depth, the erosion degree decreased significantly. Under the condition of 30 mm·h^-1 rainfall intensity, the surface of the soil was relatively intact, and the soil erosion type was splash erosion. Also, under the condition of 60 mm·h^-1 rainfall intensity, the soil erosion was all sheet flow erosion, under 10 cm and 20 cm tillage depth, spot erosion appeared in the lower part of the slope, and the soil erosion degree was lower for sheet flow erosion at 30 cm tillage depth. For the 90 mm·h^-1 rainfall intensity, rill erosion appeared on the slope while at 10 cm tillage depth, rill erosion was well developed. In addition, at 20 cm tillage layer depth, rill erosion development was significant while at 30 cm tillage depth, slope erosion was mainly sheet flow erosion.【Conclusion】 The top soil structure can significantly change the relationship between rainfall and runoff. Higher tillage layer depth can reduce surface erosion, promote the deep infiltration of soil moisture, and increase the soil's deep-water holding capacity. Also, this research can serve as a reference for the rational layout of topsoil structure, improvement of rainfall utilization rate and enhancement of soil erosion resistance in the southern red soil area.