We build a large-scale 2D tidal current and sediment mathematical model based on the Yalu River Estuary to study the water-sediment transport characteristics of Dadong waterway under the new boundary conditions.The results show that the M2 tidal isochron of the bay where the Yalu River Estuary is located is generally in the north-south direction,the tide rotation direction is counterclockwise.The M2 tidal amplitude gradually increases with the tidal wave from the outer side of the estuary towards the western waterway,reaching its maximum near the Miaogou Port Basin.The amplitude of the tidal wave deformation outside the mouth and in the western waterway can reach 20%.The flow intensity in the deep channel of Dadong waterway is obviously large,the sediment concentration in the southeast of Miaogou Port Basin is the largest,and the sediment concentration from the waters near the first harbor basin is decreasing.The Euler residual current and Stokes drift direction in Dadong waterway are seaward.The unit width tidal volume and unit width sediment transport volume at ebb tide are greater than that at flood tide.The direction of net tidal volume and net sediment transport volume is seaward.The sediment mainly comes from the mudflat of the west waterway and the mudflat on the east side of Dadong waterway.