This study is investigated vibration analysis of a FG rectangular plate partially contacting with a bounded fluid. Wet dynamic transverse displacement of the plates is approximated by a set of admissible trial functions which is required to satisfy the clamped (CL) and simply supported moveable (SSM) and simply supported immoveable (SSI) geometric boundary conditions. The oscillatory behavior of fluid is obtained by solving the Laplace equation and satisfies the boundary conditions. The natural frequencies and mode shapes of the plate coupled with sloshing fluid modes are calculated by using the Rayleigh–Ritz method based on minimizing the Rayleigh quotient. The proposed method is validated with available data in the literature. In the numerical results, the effects of volume fraction coefficient, thickness ratios and aspect ratios of the FG plates and depth of the fluid, width of the tank, and boundary conditions on the wet natural frequencies are examined and discussed in detail.