Abstract: During the piling process of offshore wind turbine foundations,a noticeable phenomenon of soil strength degradation occurs around the pile. To comprehensively understand the factors and patterns influencing the weakening of soil strength around the pile,model experiments simulating the piling process were conducted. The study investigated the variation in lateral friction resistance along the pile body with penetration depth under different hammer impact energies and for various pile sizes. A degradation formula describing the pattern of soil strength reduction was established. Furthermore,employing piling software,an analysis was performed on field measurements of pile driving for large-diameter and extra-large-diameter steel pipe piles in multiple offshore wind turbine foundation projects. The research results indicate that during the piling process,the weakening of soil strength around the pile is simultaneously influenced by both pile mass and hammer impact energy. The higher the pile mass and hammer impact energy,the greater the degree of soil strength reduction. In the analysis of pile drivability,the degradation formula established in this study can simulate the reduction pattern of soil strength during the piling process for piles of different sizes.