Abstract: Since the water and sediment regulation scheme (WSRS) was implemented in 2002, the present active Huanghe (Yellow) River delta lobe has continuously prograded seaward and the slope of delta has become steeper due to the changes of the river runoff, and riverine sediment flux and components. The impact of morphological evolution of the river mouth on the sedimentation pattern during the WSRS has become a crucial scientific issue. A Delft3D-based three-dimensional hydro-sediment coupling numerical model was established to simulate the transport and sedimentation of riverine sediment in the river mouth during the WSRS conducted in 2002, 2008, 2014, and 2019. Results show that the hydrodynamics in the area were enhanced and the river mouth progressed. Meanwhile, the along-shore transport of sediment was increased while the cross-shore transport was weakened correspondingly. The along-shore extent of the deposition was increased by ～30% while the cross-shore extent was reduced by ～27%, and the thickness and shape of deposition center were changed significantly. This study provided a reference for better understanding the hydrodynamic-morphology coupling system off the Huanghe river mouth.