Abstract: Ultra-deep well engineering is constrained by multiple factors such as high temperature and high pressure, complicated formations, ultra-long wellbores, and corrosive medium, resulting in all-around technical challenges for safe and efficient operations. Therefore, In view of the safe and efficient design control problems in ultra-deep well engineering was studied, the development overview and technical characteristics of ultra-deep well engineering were summarized.Several important theoretical and technical issues were introduced, including well trajectory prediction and fast drilling with deviation prevention, characteristic analysis and control technology of downhole drilling string vibration, prediction and design control techniques of drilling extension limit, and casing failure risk assessment and safety control, etc. In addition, research progress in China and abroad, and the latest research results of the authors’ team were introduced. Finally, some suggestions were put forward on innovative development for ultra-deep well engineering. The results suggest that the overall development of theory and techniques in ultra-deep well engineering have the typical characteristics of systematic, scientific, interdisciplinary and geology-engineering integration. Strengthening the innovative research on fundamental theoretical issues is recommended, along with key and core techniques, technological collaboration relationships, technological iteration modes, and interdisciplinary integration, so as to promote the continuous innovative development of basic theory and key techniques in ultra-deep well engineering.