To investigate the influence of different water models on the dynamic characteristics and seismic response of the converter station platform, the potential-based fluid model and the added masses model are adopted to account for the fluid-structure interaction of the converter platform. Subsequently, ANSYS is utilized to analyze the converter platform’s dynamic characteristics and seismic response. The results show that the difference between the two fluid-solid coupling models in terms of self-oscillation frequency of the converter station platform is only 1%, but the fluid-solid coupling model reduces the self-oscillation frequency by 5%-7% compared to the non-fluid-solid coupling model. Additionally, the influence of water in the inner and outer domains of the pile leg on the self-oscillation frequency is approximately equivalent. Therefore, when analyzing the seismic response of the structure, it is necessary to consider the fluid-structure interaction of the water both in the inner and outer domains of the pile leg. Furthermore, the seismic response differences between the two fluid-solid coupling models for the converter platform are relatively small (mostly within 5%). However, compared to the non-fluid-solid model, the fluid-solid coupling model exhibits a maximum difference of nearly 50% in seismic response. So, it is essential to consider the fluid-structure interaction for the seismic response analysis of the offshore converter station platform. The added masses model demonstrates simpler modeling procedures and approximately 40% reduction in computation time compared to the potential-based fluid model, making it particularly suitable for extensive computational analyses in seismic optimization design of offshore converter station platforms.