Based on China's marine geothermal resource endowment, this study evaluates the development potentials of shallow, medium-to-deep, and high-temperature hydrothermal resources, with a focus on key technological systems, development bottlenecks, and economic constraints. On this basis, a region-specific and phased development pathway is proposed: priority demonstration of high-temperature hydrothermal utilization in the deep water of the South China Sea, cascading use of medium- and low-temperature resources in the eastern coastal zone, and forward-looking research on enhanced geothermal systems and possible mineral ‒ geothermal coupling in far-offshore areas. The study further proposes a distinctive marine “Geothermal-plus” multi-energy synergistic development model, involving retrofitting of offshore oil and gas wells, wind ‒ solar ‒ geothermal hybrid systems, heat ‒ electricity ‒ water cogeneration, and heat‒electricity‒mineral coupling under suitable high-mineralization conditions. A strategic support framework is also outlined, covering technological innovation, equipment capability enhancement, policy incentives, industrial coordination, and ecological risk control. The study aims to provide a more prudent and operational scientific basis and technological support for advancing China's marine geothermal sector from resource assessment to demonstration-scale deployment.