Abstract: The Yellow River estuary refers to the section below Lijin, characterized by weak tides, less tributary water, high sediment load, and rapid floodplain extension, where sediment inflow plays a leading role in the evolution of its specific flow paths. Based on previous studies, this paper considers the joint effect of land and coastal deposits as a necessary factor in determination of the increase in river length, and develops a relationship of cumulative sediment deposition versus sediment transport at Lijin using the estuary filed measurements from 1958 to 2000. Coupled simulations of the river’s lower reaches and estuary section are carried out using a quasi two-dimensional flow and sediment transport numerical model, including calculations of the erosion and deposition of sediment and the river length of the estuary under three design flow-sediment conditions ? annual sediment inflows of 300, 600 and 800 million tons. And two river training modes, the current management mode and the “two defensive lines” mode, are compared. Results show that in either of these two modes, the estuary will take a cumulative deposition trend over the next 50 years. In the same flow and sediment conditions, more sediment will be deposited in the “two defensive lines” mode, by 2.10?108 t, 3.48?108 t and 4.20?108 t in the three design conditions respectively. And this mode will result in an extra river length increases of 1.27 km, 2.07 km and 2.49 km respectively.