Abstract: In recent years, offshore photovoltaics have become a rapidly growing sector in the field of renewable energy. Floating photovoltaics have become a new demand as offshore photovoltaic development moves towards deeper seas. The floating photovoltaic structure system with a floating pipe foundation has been widely used in inland waters. When applying floating pipe foundations to the marine environment, it is necessary to consider wave action under extreme sea conditions to ensure structural safety. This paper establishes a numerical model for the hydrodynamic action of extreme waves on floating pipes based on the open-source software OpenFOAM. Extreme waves are simulated using focused waves. The numerical model is validated by physical experimental results. With the verified numerical model, wave loads on floating pipes are analyzed. It is found that the established numerical model can accurately calculate the extreme wave action on floating pipes. The submergence depth of the floating pipe significantly influences wave loads. Wave loads on the floating pipe decrease with an increase in submergence depth. The peak frequency and maximum amplitude of the incident focused wave significantly impact the wave loads on the floating pipe. It is essential to conduct a specific analysis of wave loads on floating pipes based on the wave characteristics of the development sea area where the photovoltaic project is located. The research results have theoretical significance for the design of offshore floating photovoltaic structures' resistance to wave action.