Interdigitated electrodes piezo-actuator has been widely applied in smart structures. Based on the analogy between the equation of inverse piezoelectric effect and piezoelectric strain decomposition, the driving voltage is simulated for mechanical load in this paper. Firstly, stress simulation method of piezoelectric actuators can be employed to the static displacement of piezoelectric cantilever beam and wing-box structure. Then, a modified coefficient is needed to modify the ferroelectric properties of the high voltage of the interdigitated electrodes piezoelectric composite materials. Finally, the experimental results indicate that stress simulation method of piezoelectric actuators is valid, and it can accurately simulate deformation of piezoelectric smart structures. The Error is little, which meets simulation requirements.