Sloping lands are prone to heavy soil erosion, resulting in farmland degradation in most mountainous regions. Straw incorporation can enhance resistance to erosion by improving the soil structure and reducing runoff. Laboratory-simulated rainfall experiments were conducted on silt loam soil to measure the effect of wheat straw incorporation on soil erosion and sediment delivery processes. Different wheat straw incorporation rates (WSIRs: 0, 2, 4, and 8 t ha−1), slope gradients (SGs: 10°, 15°, and 20°), and rainfall intensities (RIs: 80, 120, and 160 mm h−1) were evaluated. The results showed that the total rainfall amount was set at 100 mm. The sediment delivery processes were measured using oven-dried runoff samples collected during the specific intervals. The experimental data revealed that sediment delivery processes increased with increasing rainfall duration and decreased with increasing straw incorporation rates, respectively. Straw incorporation significantly reduced soil losses under steep slopes (20°) and during high-intensity rainfall (160 mm h−1). Compared with the control plot, the sediment concentrations, sediment delivery rates, and soil losses of slopes with straw incorporation were reduced by 52%, 62%, and 63%, respectively. The reduced sediment delivery rate and soil loss be attributed to increased soil surface roughness (exposed straw) that intercepted runoff, increased soil infiltration, and reduced flow velocity. The incorporated straw indirectly reduced sediment concentration by improving soil structure, which resulted in a smaller reduction in sediment concentration. The sediment reduction was maximized at 80 mm h−1 or 10°, while the benefits of straw incorporation on soil and water conservation were reduced with higher rainfall intensities and slope gradients. This study can serve as a basis for guiding soil and water conservation on sloping farmlands.