Abstract: The deep and remote sea is rich in wind power resources and faces fewer constraints, making it an important direction and main battlefield for the future development of offshore wind power. Offshore electricity-hydrogen coupling is the main path to solving the problems of economic efficiency and consumption difficulties in deep and remote sea wind power transmission. The high-salt, high-humidity marine environment and the variability of wind power in the deep and remote sea bring significant differences in technology, operational efficiency, and reliability of offshore electricity-hydrogen coupling compared to onshore applications, necessitating an in-depth analysis of key technical challenges and engineering application models. Through analyzing the current status of technological development, it is believed that the movement of floating facilities makes the technology of electricity-hydrogen coupling for floating facilities more complex and demanding than that for fixed facilities. Currently, offshore electricity-hydrogen coupling is still in a critical stage of transition from "engineering demonstration" to "early industrialization". Five engineering application models are proposed, including electricity-hydrogen conversion from deep and remote sea wind power to onshore terminals, centralized electricity-hydrogen conversion in the deep and remote sea, decentralized electricity-hydrogen conversion in the deep and remote sea, integrated development of electricity-hydrogen conversion and offshore oil and gas in the deep and remote sea, and integrated development of electricity-hydrogen conversion and comprehensive energy islands. For the centralized electricity-hydrogen conversion model, the preferred choice for electricity-hydrogen conversion facilities is fixed platforms in shallow water areas. If floating facilities are used, special attention should be paid to the voltage level, current capacity, and heat dissipation issues of dynamic cables and slip rings. For the decentralized electricity-hydrogen conversion model, technical issues such as the mechanical strength and impact/vibration resistance of floating wind turbine electrolyzers, "hydrogen embrittlement" of hydrogen transmission pipelines, and the safety and integration of flexible risers or dynamic connectors should be focused on. The engineering model of electricity-hydrogen conversion from deep and remote sea wind power to onshore terminals is relatively mature and requires the integration of multiple scenarios to enhance economy; the other four models require electricity-hydrogen conversion on offshore facilities, which are currently immature. Therefore, it is advisable to first carry out demonstration projects of electricity-hydrogen integration in fixed wind farms around shallow water offshore oil and gas fields with oil and gas pipelines, gradually extending to demonstration projects of electricity-hydrogen coupling in floating wind farms around deep water offshore oil and gas fields with oil and gas pipelines, and only then considering the engineering models of decentralized electricity-hydrogen conversion and the integration of electricity-hydrogen conversion with comprehensive energy islands.