A numerical approach of a fluidstructure coupling with closely coupled algorithm was used to simulate the coupling motion between the fluid and the flexible plate. The fluid, which was modeled by the Arbitrary Lagrangian-Eulerian (ALE) formulation of the incompressible Navier-Stokes equations, was simulated by the finite volume method. The structure was described by the equation of the elastodynamics in Lagrangian representation, and was simulated using finite element approach. In order to satisfy the coupling interfacial boundary condition, the date transfer and interpolation was performed via the interface of the fluid and structure several times within one time step. The free oscillation of elastic plane in resting fluid and the VIV of flat plane behind the square head was calculated, and the amplitude and frequency of the plate vibration and the hydrodynamic load on the plate were monitored. The validity of the coupling method used in this paper was verified by comparing it with the previous work. Meanwhile, the influence of material parameters on fluidstructure interaction motion was analyzed. It was noted that larger viscosity of fluid damps had a more significant influence on the vibration amplitude of the plate more obviously. And with the increase of fluid density, the attenuation velocity of the vibration increased, while the frequency decreased. When the structure had low natural frequency, the amplitude and frequency of the coupling motion would also be small.