Abstract: Taking offshore wind power pile foundation as the research object and using the self-designed horizontal loading device to simulate wave load and using particle image velocimetry（PIV） technique to carry out scaled model tests, the cyclic deformation characteristics of soil around the pile and the variation of horizontal bearing capacity of offshore wind turbine pile foundation before and after loading were studied in this study. The results reveal that the cumulative rotation angle of pile top exhibits a three-stage variation characteristic of linear growth, slow growth and steady development with the number of loading. The soil around pile exhibits a classic two-region damage pattern. The variations in loading amplitude have a considerable impact on the soil displacement vector field and displacement nephogram effect range in the passive area to the right of the pile. Hysteresis is clearly visible in the load displacement curve at the top of the pile, meanwhile, as loading times increase and cause cumulative displacement, the hysteresis circle shifts to the right. Accompanied by the reduction of the hysteresis loops area and the increase of the secant stiffness, the soil varies from plastic deformation to elastic deformation as the dominant change. After cyclic loading, there is a sizable pinch in the hysteresis loop, which weakens the energy dissipation capacity. In comparison to before loading, the pile foundation’s horizontal bearing capacity and elastic deformation capacity have greatly increase.