As offshore wind energy industry advances into deeper water recently, jacket foundations become one of the predominant support structure types for far-sea wind farms. To ensure the safety and reliability of offshore wind turbine (OWT) jacket foundations in the complex environments of far-seas, the investigation of their resistance capabilities to extreme ocean wave is essential. In this study, the OWT jacket foundations in the sea area of Cangnan and Lianjiang are adopted to conduct a typical case study. This study employs a full-scale jacket foundation to carry out some full-scenario, large-scale hydrodynamic numerical simulations considering the combined action of wave and current. It is revealed that for OWT jacket foundations in Cangnan and Lianjiang, China, under an extreme condition with approximately 26 m wave height and 18 s wave period, the peak wave impact and horizontal force on the jacket foundation are approximately 190 kPa and 18,000 kN, respectively. Furthermore, this study discusses the wave profile evolution characteristics around the jacket foundation and the correlation between wave run-up and wave height. These findings provide a good case study and technical reference for the full-scale fine simulation of wave forces on OWT jacket foundations in far-sea areas.