Abstract: The conventional analysis of the transient flow and the correspondingdynamics response of a structure in the piping systemis separated, and the interaction between them is often neglected. In this paper,the transient model and the mechanism of Fluid-Structure Interaction(FSI) under the multiphase flow transportation in the oil/gas industryare introduced. Afluid-structure interaction model for gas-liquid transient flow withoutshin-wall assumption is developed. Comparisons of the model with othersshow that the presentmodel can be applied to more general cases in theexperiment and/or numerical simulation.