Abstract: As more and more oil and gas resources are discovered in deepwater worldwide, the deep water drilling has become more and more in recent years. It requires more on drilling engineering and drilling technologies due to the increased water depth and complicated marine conditions. Based on the practice in deep water drilling both at home and abroad, some key technologies are discussed in this paper, including the drilling equipment, the positioning system, the casing program design, the dual-gradient drilling technology, the technology of jetting and lower circuit, the dynamic killing and drilling technology, the technology of annulus pressure detection while drilling, the technology of drilling fluid and cementing, the drilling raiser technology, and the blowout preventer system. All the technologies play an important role in enabling drilling design and construction to expand into deep water.