Abstract: Deep and ultra-deep oil and gas are important replacement resources for increasing reserve and production in China. Therefore, to achieve safe and fast drilling and completion of deep and ultra-deep wells is of great significance for the efficient development of deep and ultra-deep oil and gas resources. By reviewing the development history of deep and ultra-deep wells in China, the paper summarizes and compares the current development status, advance and application of key technologies for deep and ultra-deep well drilling and completion, and further points out the development direction based on the current main problems. Moreover, a comparison has been made on key drilling equipment for well drilling and completion in deep and ultra-deep wells, wellbore structure optimization and expansion, drilling speeding-up, drilling fluid, cementing, downhole measurement and control technology, and key technical performance indicators of oil testing and completion technology and its application status in China and other countries. Then it is pointed out that technical gaps mainly occur as the result of resistance to high temperature and pressure, as well as high stability. Further, an analysis is performed on the latest progress and application of high-end equipment, cutting-edge tools and core additives, including the automatic drilling rigs for deep drilling that can support China to achieve the normalization of 8 000-meter ultra-deep drilling on land, with the drilling capacity of 9 000 meters and drilling depth range extending towards 10 000 meters, wellbore structure optimization, controlled pressure drilling (MPD), efficient PDC bits, high-temperature resistant and ultra-high density oil-based drilling fluids, efficient plugging, high strength and toughness cement slurry, automatic cementing, high temperature resistant acid fracturing, coiled tubing equipment for deep and ultra-deep operation. In view of ultra-high temperature, ultra-high pressure, complex geo-stress and multi pressure systems in ultra-deep layer which pose a great challenge to safe and efficient drilling and completion, the paper proposes that the further research should focus on optimization and expansion of wellbore structure, high temperature and high pressure resistant downhole tools and instruments, ultra-high temperature resistant downhole fluids, efficient rock-breaking and speed-up tools for ultra-deep drilling, ultra-high temperature and pressure resistant testing and completion tools, ultra-high temperature resistant and low damage acid fracturing fluid, digital intelligent drilling and completion equipment and technology, so as to accelerate the breakthrough and iterative upgrade in key technologies and equipment, support and safeguard the efficient exploration and development of deep and ultra deep oil and gas resources.