Abstract: Based upon piezothermoelastic material governing equations, the homogeneous state equation for the mechanical, electric, thermal coupling problem of piezothermoelastic materials is derived by means of reforming the constitutive equations of piezothermoelastic materials as well as combining the piezothermoelastic material thermal equilibrium equations. The homogeneous state equation can be solved independently through the precise integration method. The treatment simplifies the solution programs often used to solve second order differential equation on the thermal equilibrium and gradient relationship, and decreases greatly the workload of numerical computation.