The “Deep Sea One” energy station is the first ultra-deep-water large-scale gas field that is independently explored and developed by China and its proven reserves of natural gas exceed hundreds of billions of cubic meters. This energy station is also the first 100 000-ton deep-water semi-submersible production, storage, and offloading platform worldwide; it adopts a whole sea development mode that integrates a semi-submersible production, storage, and offloading platform, a subsea production system, and submarine pipelines. Moreover, the energy station is built by conducting independent design, optimizing organization and management, and strengthening technical research and innovation. This paper first reviews the construction background and challenges, introduces the optimization and breakthroughs of the development modes of deep-water gas fields, and then summarizes the major technological breakthroughs and experiences during the design and construction of this energy station, including oil storage in columns of semi-submersible platforms, load lateral transfer of super-tonnage open structures via pre-inclination and return, and half-floating integrated precisely of super large structures. This study is hoped to provide a useful reference for efficient development of deep-water and ultra-deep-water oil and gas fields and for high-level construction of semi-submersible platforms.