Abstract: The silting mechanism downstream of sluices and limits of the 2-D suspended sediment model to simulate the silting downstream of sluices in a tidal reach are analyzed.A new method is presented: the average silting thickness in the reach approaching the sluice is predicted by an analytical model,and the silting distribution in the other reach is predicted by a 2-D suspended sediment model.Analysis results of an example show that this method can supply the foundation for the feasibility study of sluice construction in the estuary.