Abstract: To explore the change of structural dynamic characteristics of wind turbine pile before and after scouring, a 10 MW single-pile offshore wind turbine model was established under soil-structure interaction. The modal analysis of the whole machine and the dynamic response analysis of the wind turbine influenced by the wind and wave were carried out. Results show that with the increase of scour depth, compared with the first order frequency, the second order natural frequency decreases significantly, and the erosion effect has a significant impact on the second order natural frequency. Compared with no scouring, the displacement of the tower top increases by 7.8% and the displacement of the pile foundation increases by 110.5% at the scour depth of 1.28D. Compared with the tower, the scouring effect has a greater impact on the pile foundation. Compared with no scouring, when the scour depth is 1.28D, the peak stress of the pile foundation increases by 14.3% and the peak strain energy increases by 6.7%. The scouring effect makes the accumulation of stress and strain energy more obvious. The impact of the scouring effect on the wind turbine should be fully estimated in the design.