Based upon the generalized Hamilton variation principle, the non-homogeneous Hamilton canonical equation for piezothermoelastic bodies was derived. Considering the symplectic relations of variations in the thermal equilibrium formulations and gradient equations, the non-homogeneous Hamilton canonical equation was transformed into homogeneous equation for solving independently the coupling problem of piezothermoelastic bodies by increasing the dimensions of the canonical equation. The treatment, by which the non-homogeneous equation was transformed into homogeneous equation, not only simplifies greatly the solution programs, but also reduces the workload of numerical computation. The numerical response of the laminated piezothermoelastic plate with four simply supported edges under thermal and dynamic load was studied. Part of examples was compared with relative reference.