Ocean thermal energy coversion (OTEC) is environmentally friendly, has huge resource reserves, and offers stable power output. However, its commercialization has been slow. The fundamental bottleneck lies in the limited natural temperature difference, which leads to existing thermal cycle efficiencies generally remaining below 5%, far lower than those of conventional thermal power plants and even other renewable energy sources. Based on a systematic review of OTEC, this study proposes a concept of ocean large-temperature-difference energy generation, leveraging ocean geothermal energy and deep cold seawater, while considering multi-level utilization such as cold energy utilization of liquefied natural gas, seawater desalination, and extraction of ocean-associated strategic minerals. It analyzes the technical and equipment feasibility of ocean large-temperature-difference energy generation, proposes an engineering model for this technology, and identifies key engineering directions: efficient thermal cycle and thermal conversion technology and equipment for ocean large-temperature-difference energy generation, equipment for harnessing ocean geothermal energy, and technical devices for extracting ocean-associated strategic minerals. The study advocates for intensified exploration of ocean geothermal energy and ocean-associated strategic mineral resources. Moreover, it is imperative to address core technologies and key equipment for ocean large-temperature-difference energy generation, seawater desalination, and the extraction of ocean-associated strategic minerals. It is also essential to expedite the establishment of demonstration projects, supplemented by precise policy and investment support, thus to promote the commercialization of ocean large-temperature-difference energy generation, facilitate the efficient and integrated utilization of ocean energy resources in China, and contribute to China's energy security and high-quality development of the marine economy.