The steep slopes of actively developed gullies are extremely sensitive to erosion in the Mollisol region of Northeast China; however, decision making on the optimal configuration for gully bank protection is under discussion. Here, five vegetation communities were established on regraded gully banks with bare slopes as the control to identify their controlling effects on flow hydraulics and soil erosion through in situ scouring experiments. A hydraulic flume experiment was conducted to clarify the ability of roots to reduce erosion. For vegetated slopes, flow velocity, stream power, and unit stream power decreased by 42-67%, 0-18%, and 44-68%, respectively, while flow depth, shear stress, the Darcy-Weisbach friction coefficient, and Manning coefficient increased by 55-150%, 69-156%, 5-22-times and 2-5-times, respectively. Changes in the seven flow hydraulic parameters were significantly influenced by vegetation coverage, aboveground biomass, root mass density and litter biomass (p < .05). Consequently, the five vegetation communities experienced decreased runoff and soil loss by 19-30% and 78-97%, respectively. Vegetation with tap-roots and rich roots of 1.0-2.0 mm in diameter was more effective in controlling gully bank erosion. Thus, the vegetation community consisting of Dactylis glomerata, Festuca arundinacea, Uraria crinita and Medicago sativa (25:25:25:25) is perfectly acceptable for gully bank protection in the Mollisol region of Northeast China. The results provide a scientific reference for selecting optimal vegetation configuration for gully bank rehabilitation.