This paper deals with seismic response of a simply supported laminated composite plate subject to vertical motion of all supports. The vertical motion is defined in terms of a seismic displacement response spectrum. Single-point response spectrum analysis is used for the spectrum analysis. Finally, the non-dimensional fundamental frequency is obtained. The numerical studies are conducted to determine the effects of width-to-thickness ratio, degree of orthotropy, fiber orientations and aspect ratio on the results. The problem is modelled using finite element package program ANSYS. The results are given in tabular and graphical forms and obtained results are compared.