Abstract: The water depth achieved by deepwater drilling in the South China Sea has been increasing annually, and three wells have been already drilled at a depth of more than 2000 meters, and the maximum depth exceeds 2600 meters. The increasing water depth results in the prolonged tripping time for drilling tools during operations in deep water, particularly ultra-deep water, and operational safety risks are increased due to the long-time exposure of drilling tools to deep water for extended periods. To reduce the frequency of tripping in deep water and enhance the efficiency of operations in shallow formations, the paper proposes an efficient "three-in-one" drilling technology for shallow formations in deep water, which is based on the analysis of regional shallow geological and mechanical parameters and practical experience from over 40 deepwater wells drilled in the South China Sea. Through the optimization of wellbore structure design, drill string and tool optimization, jet bit design, and subsea wellhead stability analysis, the "three-in-one" efficient drilling operation mode for shallow formations in deep water has been developed. This technology allows for the completion of the whole wellbore comprising surface conductor, surface casing, and intermediate casing in a single trip through innovative designs of drilling tools and tubular structure, thus simplifying operational procedures, significantly enhancing operational efficiency, and achieving the goal of deepwater drilling. The technology was applied in 10 deepwater wells in the deepwater areas of the South China Sea, such as Baiyun, Liuhua, Liwan, and Kaiping. The application results indicate that the "three-in-one" efficient drilling technology for deepwater shallow formations can reduce tripping operations by two trips compared to conventional jetting methods, by which the drilling efficiency in deepwater shallow formations can be increased by over 50 % , and the exposure time and frequency of drilling tools in deep water is also reduced.