Abstract: The state equation of functionally graded rectangular plate subjected to time-dependent thermal loads was established based on the three-dimensional linear thermoelastic theory and using state space approach, in which three displacement components, three stress components, temperature components and a heat flux component were chosen as state variables. The state equation took into account the motional inertial item and the coupling effect during heat conduction. A simply supported three dimensional functionally graded rectangular plate was analyzed assuming the mechanical properties of the materials exponentially distributed along the thickness. The transient thermal responses due to a thermal shock on its top surface were obtained using the Laplace trans-formations and shooting methods. Effects of the volume fraction distributions of constituent materials on the ther-mal responses, including the temperature change, the displacement and the stress distributions were investigated.