Abstract: Sediment deposition is one of the key issues during the processes of reservoir construction and operation. On the basis of the observed sedimentation patterns in the dam area of Three Gorges Reservoir (TGR), a schematic diagram of fine-grained particles sedimentation in the dam area was proposed. Critical slope was used to judge the incipient motion of the fine-grained deposits. It was assumed that the mass transport processes of fine-grained deposits were dominated by the shallow flow equations. A numerical method of gravity-driven motion of fine-grained deposits was developed and combining with a 3-D flow and sediment transport model. Then, the sedimentation patterns of fine-grained particles in the dam area of the TGR were simulated by the developed method. The simulated results agreed well with the measured data. Sediment deposits in the dam area are mostly found at the bottom of the main channel, which have reshaped the river bed with a flat surface that is nearly horizontal. In contrast, very little fine sediment deposits can be found on the bank slopes of the channel. The developed method can be applied to improve our understanding of fine sediment transport mechanisms in large reservoirs.