Abstract: Based on the FVCOM circulation model, the synthetic wind field is formed by coupling the ECMWF background wind field and Jelesnianski typhoon empirical model to simulate the hydrodynamic situation of 9711 typhoon “Winnie” passing through the coastal wetlands of Liaohe Estuary. We add an additional source terms into the momentum equations and turbulence equations to express the resistance of salt marsh vegetation on hydrodynamics. The model is verified with measured tidal level, flow velocity, flow direction and other data in the study area. It shows that the simulated results are in good agreement with the measured data since the salt marsh plants on the tidal flat show no obvious influence on the process of tide level. Besides a significant attenuation effect on the flow velocity, the attenuation effect of Phragmites australis on flow velocity at a maximum attenuation rate 81.43% is greater than that of Suaeda salsa. In addition, the track of typhoon has a great influence on the storm surge and flow velocity in the coastal wetlands of Liaohe Estuary. The stronger the typhoon is, the greater the storm surge and flow velocity caused by the storm surge in the local area.