A flexible mechanical structure can provide an additional function, such as a kinematic function if flexibility is implemented in some appropriate portions. We can also construct so-called flextensional actuators or transducers by combining the flexible structure with piezoceramic material. In this study, we present a methodology to obtain flextensional actuators using the homogenization design method. First, the mean transduction is formulated using a mutual energy concept. Second, we propose a new multi-objective function incorporating the maximization of the mean transduction and stiffness. Next, an optimization procedure is constructed based on the homogenization method and sequential linear programming (SLP). Finally, some examples are presented to confirm the problem specifications of the optimal configurations.