The level of marine science and technology is an important indicator of a country's scientific and technological strength. Under the global trend of green energy and low−carbon transformation and the guidance of the "dual carbon goals", marine energy resources have become an important growth pole for ensuring China's energy security. This paper selects six representative subfields in the marine field, comprehensively analyzes the development trends, demands and challenges of engineering science and technology, and uses the strategic research method of technology foresight. Combined with the vision of economic and social development, it innovatively distills 10 key technologies, 10 common technologies and 3 disruptive technologies. It proposes a three−in−one strategic framework for China's marine engineering science and technology development in 2040: "possessing an advanced and independent marine equipment and technology system, enhancing the green development capacity of marine energy and resources, and establishing a technical guarantee system for marine security and strategic interests", as well as six major marine science and technology projects: demonstration of comprehensive development of offshore energy, global intelligent space−air−ground−sea integrated marine information networking, green development of marine mineral resources, construction of an all−round marine environment monitoring network, development of biological resources in polar and oceanic high seas, and green development of China's exclusive economic zone fishery. The research suggests: strengthening the top−level design in the field of marine engineering science and technology, and doing a good job in overall planning; giving full play to the advantages of the system and mechanism, and realizing the integrated application of industry− university−research− use; strengthening independent innovation, and forming high−quality development of technology and equipment; deepening international exchanges and cooperation, and enhancing international discourse power; innovating the mechanism and system of marine talents, and strengthening talent cultivation and transformation of achievements; increasing investment in research and development, seizing new opportunities for leapfrog development, and helping China realize the grand blueprint of a marine power as soon as possible.