Abstract: The applicability of simplified model of Biot's dynamic consolidation equation to response of horizontal vibration of piles is analysed. The potential functions are introduced to decouple the governing differential equations, and then the analytical solution neglecting the vertical continuity of soil and water is derived. Based on the previous researches, the impedance functions of the head of piles are discussed using the single-phase soil model, the equivalent single-phase soil model and the model neglecting fluid inertia term and vertical continuity of soil and water, the model considering fluid inertia term and neglecting vertical continuity of soil and water, and the model considering fluid inertia term and vertical continuity of soil and water. It is concluded that the conditions of Biot’s dynamic consolidation equation can be simplified.