[Objective] Evaluating the patterns of soil erosion on soil slope in the Xin'an river basin can provide scientific support for regional soil erosion control and sustainable ecological development. [Methods] Through artificial rainfall simulation experiments, this study systematically analyzed the runoff and sediment yield processes under different rainfall intensity and slope combinations for two typical soil types—yellow soil and red soil—within the basin. It also examined their differential erosion characteristics and established a quantitative relationship model between hydrodynamic parameters and sediment yield intensity. [Results] (1) Both runoff and sediment yield rates on yellow and red soils exhibited a steep initial increase followed by gradual stabilization during rainfall onset, with both increasing with higher rainfall intensity and slope gradient. Red soil slopes demonstrated higher runoff and sediment production capacity than yellow soils, particularly under 60 mm/h rainfall intensity. (2) Rainfall intensity and slope gradient collaboratively exacerbated hydrosediment erosion, with rainfall intensity primarily driving runoff and sediment transport on red soil slopes. When the slope reached 15°and rainfall intensity increased to 60 mm/h, the contribution of slope to sediment loss on yellow soil slopes increased to 59.06%. (3) A high correlation existed between runoff and sediment yield on both soil types. Yellow soil slopes generally exhibit a nonlinear relationship characterized by Y = a/(1 + exp-b*(X-c)), whereas red soil slopes, due to rapid saturation caused by poor structure, show synchronous linear growth in sediment and runoff yield at 60 mm/h rainfall intensity, described by the function Y = a + b*X. (4) Among the slope hydraulic parameters, the average velocity (V) could effectively predict the sediment yield trend of yellow soil (R2=0.52), while the Froude number (Fr) was more suitable for the sediment yield dynamics of red soil (R2=0.44). [Conclusion] This study clarified the coupling mechanism of rainfall intensity and slope of soil gradient in slope erosion within Xin'an river basin, providing a theoretical basis for formulating differentiated soil and water conservation strategies. It is suggested that rainfall intensity regulation should be strengthened in red soil areas, while slope management should be emphasized in yellow soil areas to curb accelerated soil erosion.