The performance of a barrel stave flextensional transducer is determined by the properties of its constituent materials and the effects of many structural parameters. In this study, with the finite element method, the structure of a barrel stave flextensional transducer was optimized to achieve the widest bandwidth while satisfying the requirements on pressure and center frequency. The optimization was carried out with the SQP-PD method for multi-variable minimization. The optimized barrel stave flextensional transducer satisfied all the required specifications.