The interaction between raindrop splash and concentrated flow affecting soil detachment capacity (Dc) on gentleto-steep slopes has rarely been studied. Three series of experiments (upstream inflow, raindrop splash, and upstream inflow with rainfall) were conducted on clay loam soil across different slope gradients. Results indicated that Dc was in the 0.0043 to 0.0058 kg m- 2 s- 1 range under raindrop splash conditions and in the 0.011 to 4.81 kg m- 2 s- 1 range under upstream inflow conditions. Compared with raindrop splash, concentrated flow scouring more significantly affected Dc. The presence of raindrop splash increased Dc by 6.45 %-85.64 % under lower unit width inflow discharge conditions and predominantly on gentler slopes under a limited number of experimental conditions. This result was attributed to the dominant effect of the additional flow discharge from rainfall-induced runoff, increasing the flow energy. Conversely, under most experimental conditions with higher inflow discharges and steeper slopes, raindrop splash reduced Dc by 10.44 %-81.91 %, which was attributed to the intensified turbulent motion and flow resistance, decreasing the flow energy. The relationships between Dc and slope gradient varied for gentle and steep slopes. A critical Dc threshold of 10 degrees-12 degrees slope gradients distinguished between gentle and steep slopes across all experimental treatments. The contribution of raindropimpacted concentrated flow to Dc increased rapidly at lower flow discharges and on gentler slopes. Still, it increased more slowly at higher flow discharges and on steeper slopes. The contribution of raindrop-impacted concentrated flow to Dc ranged from 49.84 % to 99.78 %. The Dc reduction rates for this interaction effect ranged from -33.36 % to 82.02 %. This study revealed the interaction between raindrops and concentrated flow on Dc and established a slope threshold for Dc. These findings elucidate the mechanisms underlying soil detachment driven by raindrop-impacted concentrated flow and facilitate the development of process-based soil erosion models.