Abstract:A three dimensional thermoelastic analysis on functionally graded plates with arbitrary graded distributions is conducted. From the basic equation of thermoelasticity for the orthotropic functionally graded material plates, assuming the distribution functions of the plate thickness are arbitrary, the Peano Baker series solution is obtained when the plate is subject to thermal and mechanical loads on its top and bottom surface based on the state space method. Through numerical examples, the convergence of the present series solution is investigated; the effects of different material gradient distributions on displacement, stresse and temperature of the plate are also discussed in detail.