The wave and tidal current are the important factors for the sediment transport of silt coast. United the third generation wave model SWAN for shallow water, this paper approximated the wave motion as time-averaged wave flow distribution field. And based on the wave flow radiation stress, a 2D mathematical model for sediment transport by wave and tidal current has been established. Based on triangle grid and finite volume method, The Roe scheme based on Riemann solver is used to compute the flux in the paper. The result shows that the wave is the main dynamics factor for the bedload movement. Wave-current interaction has a significant impact of sediment transport. The suspended sediment concentration increased more than 5 times when the typhoon landfalling. And it the main cause of scour for the shoal area during typhoon. The model has been verified by the topographical data of trial dredging area at Cangnan thermal power plant. And it replayed the sudden sedimentation caused by typhoon. The research is very significance for the sediment transport of silt coast.