Abstract: Based on the analysis of gas-fluid dual-phase flooding phenomenon, this study proposes a well kill method of dynamic displacement that involves kill fluid injection and simultaneous gas expulsion. In a theoretical process of well killing, dynamic displacement maintains constant bottomhole pressure; gas expulsion complies with the law of conservation of matter; and killing fluids fall downward to bottomhole, satisfying flooding conditions. Thus, a calculation model for well killing parameters of dynamic displacement is established. Gas-fluid injection rate ratio and maximal kill fluid injection rate estimated using the proposed model are close to the Ramtahal experimental data, demonstrating that the model is applicable for use in calculation of on-site well killing parameters. Comparison of well killing curves between dynamic and static displacement shows that at a relatively low killing rate, dynamic displacement involves a shorter period and lower wellhead pressure than static displacement. In terms of equipment safety and technology of well control, dynamic displacement is superior to static displacement. Finally, a well killing procedure of dynamic displacement is given, which provides a reference for on-site well killing operation.