Abstract: Combined with the piezoelectric stack actuator, statically indeterminate truss becomes adaptive structure. The piezo-electric FEM equation of mech-electric coupling is deduced by using Hamilton's principl, on the basis of which the sensitivities of stresses to voltage are acquired. Regaiding the input voltage as control variables, the programming model of static strength control is constructed. The correctness and efficiency of the method are illustrated by several examples.