In the estuarine and coastal engineering, numerical modeling of tidal current has become a popular and preferred approach to study the hydrodynamic environment. However, it is still difficult for direct simulation of small structures such as jetty, pier, offshore platform in a large-scale domain among the 2-D numerical models for calculating tidal current. The traditional method to deal with the problem mainly adjusted the friction coefficient and local topography in a local model, but these coefficients are difficult to be determined. In this paper, to study the impact of the foundation structures of offshore wind energy plant on hydrodynamic conditions, a 2-D hydrodynamic numerical model was developed, including the Yangtze Estuary and the Hangzhou Bay. The grid can be discretionary refined as a non-structure triangle or regular rectangle so that those piers can be described as impermeable elements. The verified computation indicates that the influence is related with the characteristics of tidal current and the arrangement of foundation structures. As far as the Shanghai Offshore wind power stations are concerned, the impact on the tidal currents is limited in the region around the structures.