With the development of offshore oil exploitation into the deepwater region, we encounter a series of difficulties and challenges in practice in the South China Sea during deepwater operation. The severe natural environment puts forward higher technology standards and requirements on deepwater well completion. In the aspects of well completion tools, equipment, construction technology and strategy, there exists obvious difference between deepwater tasks and shallow water or land operations. According to the characteristics of deepwater operation, some difficulties and key technologies are analyzed. The completion sand control, perforating technology, and fracturing filling technology are studied separately. In the deepwater well completion practice in South China Sea, the possible risk points and technical solutions are summarized. The results can provide reference for the subsequent design and operation.