New conceptual designs for floating offshore wind platforms (FOWPs) are crucial for deep-sea wind power generation, increasing power output, lowering construction costs, and minimizing the risk of damage. While there have been various conceptual designs, tailored solutions for the South China Sea are limited due to the relatively harsh environment. This study proposes a novel 10 MW FOWP—“SparFloat”, which combines the advantages of a semi-submersible platform and Spar platform to cater for the sea conditions of the South China Sea. By systematically adjusting the distance between columns and the diameters of the side column and heave plate, the impact of geometrical changes in the platform on its dynamic response is investigated for the purpose of design optimization. The results highlight that roll/pitch natural periods are predominantly governed by restoring stiffness, whereas heave motion exhibits a higher sensitivity to added mass and radiation damping. Increasing the inter-column distance and side column diameter enhances stability and reduces roll/pitch natural periods, while enlarging the heave plate diameter extends the heave natural period. Time-domain simulations using a coupled FAST-AQWA framework confirm that the optimized design meets rule requirements, verifying the robustness and suitability of the SparFloat concept for the challenging environment of the South China Sea.