Introduction  The purpose is to study the influence of tidal current and wave on the sub-aqueous foundation of wind turbine in offshore wind farm.

  Method  Through two seabed topography surveys, the changes of seabed topography were compared.

  Result  The study shows that the erosion of the foundation of offshore wind turbines mainly occur in the direction of local tides. In the early stage of construction, a deep scour pit will be formed, and scour troughs will appear after two years, and siltation will appear around the foundation after the scour troughs are formed.

  Conclusion  Long-term monitoring of the foundation erosion of offshore wind turbines is helpful to understand the changes in the extent and depth of erosion. Hydrological surveys will help to establish ocean hydrodynamic models to predict the foundation erosion of wind turbines. Measures such as rock dumping and solidified soil should be carried out for erosion filling to delay the occurrence of erosion.