This paper deals with the dynamic response of Very Large Floating Structures (VLFS) in regular waves considering the deflection wave propagation (VLFS-wave) using a simple beam or plate modeling. Firstly, two kinds of dispersion relations of the VLFS-wave are derived based on the analogy of linear water wave theory, and it is shown that the eigen functions of the VLFS-wave are independent, but not orthogonal. Next, the function separation method-the method for obtaining the relationships among progressive waves-which are the incident wave, reflecting wave, VLFS-wave, and so on, is proposed. Finally, using this method, the stationary wave, reflection and refraction waves of the VLFS are considered. The law of reflection and refraction between the incident wave, reflecting wave and the VLFS-wave are derived, and the simplified dynamic response formulae are proposed for the stationary wave of a 2-dimensional beam, and for a semi-infinite large plate in which case the stationary wave is neglected.