Abstract: Based on the dynamical theories of water wave and of Mindlin thick plates, the dynamical behaviors of the steady forced oscillations of a floating elastic plate acted upon by a localized external load are presented using the Wiener-Hopf technique. The fluid is supposed to be incompressible and inviscid and the flow is supposed to be irrotational. Firstly, the problem of guided waves in two different domains with even depths is analyzed. Then the hybrid boundary value problem is reduced to solving an infinite system of linear algebraic equations. Secondly, the distributions of the deflection and the bending moment in plates under those cyclic loadings are investigated. Finally, for the cases of different external periodic load, the effects of the load application point on the distributions of the deflection in plates are analyzed.