ABSTRACT The sediment transport capacity of overland flow is a key parameter in soil erosion models, and accurately predicting this capacity is a critical challenge. Existing studies often overlook the effects of geomorphological changes and the interactions between runoff and sediment transport in actual soil erosion processes. This study conducted indoor experiments on movable beds under various inflow conditions and slopes. It evaluated the applicability of existing sediment transport capacity equations and established a new equation suitable for the Loess Plateau using dimensional analysis. The results show that among the selected classic sediment transport capacity equations, the Liu equation had the best performance ( R 2 = 0.806, NSE = 0.781, RMSE = 0.018 kg·m −1 s −1 ), followed by the Luan equation ( R 2 = 0.772, NSE = 0.693, RMSE = 0.021 kg m −1 s −1 ), the Abrahams equation ( R 2 = 0.715, NSE = 0.390, RMSE = 0.029 kg m −1 s −1 ), the Govers equation ( R 2 = 0.709, NSE = 0.320, RMSE = 0.031 kg m −1 s −1 ), and the Yalin equation ( R 2 = 0.618, NSE = −0.3, RMSE = 0.043 kg m −1 s −1 ). Correlation analysis revealed that stream power and friction velocity significantly influence sediment transport capacity ( p < 0.05). Based on these findings, a new equation for sediment transport capacity on steep loess slopes under movable bed conditions was developed and validated ( R 2 = 0.925, NSE = 0.908, RMSE = 0.011 kg m −1 s −1 ), significantly improving prediction accuracy compared to the five selected empirical equations. This study presents a new equation for sediment transport capacity of overland flow applicable to steep loess slopes, derived from existing equations for sediment transport capacity of overland flow, offering more reliable support for the development of soil erosion models in the Loess Plateau.