The multi-scales method is used to derive third-order equations of gravitational bending oscillations of a thin elastic plate floating on the surface of a homogeneous perfect incompressible fluid of finite depth. The equations incorporate the compressive force and nonlinear acceleration of vertical displacements of the plate. Based on these equations, the deflection of the plate and the velocity potential of the fluid induced by a traveling periodic wave of finite amplitude are expanded into asymptotic series to terms of the third order of smallness. The dependence of the oscillation characteristics on the elastic modulus and thickness of the plate, compressive force, the initial length and steepness of the wave is analyzed Keywords: thin elastic plate, fluid of finite depth, gravitational bending oscillations, initial wave length, wave steepnessIntroduction. The oscillations of a floating elastic plate were studied in a linear formulation in [2,7,8,11,14] disregarding the compressive force and in [1,6,10,[12][13][14] taking the compressive force into account. The nonlinear oscillations of a floating absolutely flexible plate were studied in [9]. The finite-amplitude bending oscillations of a floating elastic plate were analyzed in [3,4] disregarding the fact that the acceleration of vertical displacement is nonlinear.We will study the oscillations of a longitudinally compressed elastic plate floating on the surface of a homogeneous perfect incompressible fluid of constant depth in which a periodic wave of finite amplitude propagates. We will use the method of multiple-scale asymptotic expansions [5] and take into account the fact that the acceleration of the vertical displacements of the plate is nonlinear.1. Problem Formulation. Governing Equations. Consider a thin elastic plate floating on the surface of a homogeneous perfect incompressible fluid of constant depth. The plate and fluid are unbounded in the horizontal directions. Let the oscillations of the plate be nonlinear and the motion of the fluid be potential. With dimensionless variables x kx = 1 , z kz = 1 ,