During the recent decades, offshore wind power has been developing rapidly, and the scale of wind farms has become larger and larger. The impact of wind farms on the marine environment and topography should be paid more attention. This study applied a 2HD mathematical model to investigate the hydrodynamic and topographical changes caused by an offshore wind farm on a muddy coast. The simulation results revealed that the installation of the wind turbines did not sufficiently affect the hydrodynamic and geomorphology of the study area from a macroscopic perspective. The hydrodynamic and geomorphological changes (i.e., sediment erosion and siltation) engendered by tidal flow and waves before and after the installation of offshore wind turbines are mainly distributed inside and near the wind farm and pose little impact on the nearby channels.