Abstract: On the basis of Biot’s theory and the up formulation, governing equations for dynamic problem in two-phase media are derived. Displacements of solid phase and pore pressure of fluid phase are the two basic unknown variables. The updated Lagrangian method and Jaumann stress rate are adopted for large deformation analysis of the coupled problem. A saturated soil column subjected to step and dynamic load is numerically simulated by the proposed method, and comparison between large and small strain solutions is made.