Deep-sea underwater technology and equipment are crucial aspects to cognize the deep sea, exploit deep-sea resources, and protect the marine ecosystem. Expanding the deep-sea space faces complex environmental challenges and urgently requires support of high-level deep-sea underwater technologies and equipment. This study analyzes the components and demands for the deep-sea underwater technology and equipment and reviews the current status and development trends of the technology and equipment from four aspects: deep-sea observation/detection and perception, underwater construction, deep-sea oil and gas production, and deep-sea mineral resource collection. Moreover, this study analyzes the development status and engineering challenges in China, explores the key technology and equipment systems and key physical–mechanical mechanisms behind them, and summarizes the typical equipment and corresponding diagram. Additionally, the common key technologies of the deep-sea underwater equipment in China are summarized, including the intelligent and automation technology, precision component processing and manufacturing technology, high-precision positioning and navigation technology, high-speed communication technology, computational and analytical mechanics of large systems, and multiscale engineering design methods and technologies. Furthermore, countermeasures and suggestions are proposed aiming at achieving high-quality development of the deep-sea underwater technology and equipment in China: strengthening the top-level design of deep-sea underwater engineering to promote the establishment of a coordinating system for common key technologies, enhancing the industry influence of Chinese deep-sea underwater technical standards to explore the international market, promoting the construction of compatible and universal platforms with high quality, and training innovation professionals to provide support for the high-level development of the marine science and technology industry.