Deepwater relief wells exhibit characteristics of high risk, high technology, high investment and high social sensitivity. When the well is out of control and the routine rescue measures fail, relief well is regarded as the ultimate rescue means. However, in China, the quantity of relief wells is relatively small, and the deepwater relief well experience is almost blank at present. Based on the research of relief wells at home and abroad, a series of key technologies of deepwater relief well are sorted and analyzed. Several key technologies such as location selection, the trajectory of relief well connected, well control and well abandonment are analyzed. The results provide certain reference for subsequent relief well study.