Abstract: The transient analysis of fluid-structure coupling system is conducted using finite element method, in which the transient contact force of the unlimited contact points coupling in the contact interface between fluid and structure is taken as unknown variable. The 2-dimensional 8-node element and the contact point couple elements are used, based on the interpolating function feature in the fluid and structure domain. The fluid-structure coupling system is divided into elements, and the finite element equation with the contact constrain matrix that reflects the mechanism of interaction is derived from a variational principle. A computer program is developed for the transient analysis of fluid-solid coupling system. Numerical results are in excellent agreement with those of the available analytical solution.