Abstract: Torsional piezoelectric actuators have important applications in the felds of ultrasonic processing,piezoelectrice sensor,microdroplet generation and so on.However,they meet the problems of dficult processing and manufacturing of piezoelectric ce-ramic plates,and complicated structural design of the actuator structure,seriously restricting their applications.In order to solvethe above problems,a novel surface-bonded type torsional piezoelectric actuator is proposed.It uses square piezoelectric ceramicpieces with a special arrangement which are polarized along their thickness direction to excite the torsional vibration of a rectangularbeam structure.The proposed piezoelectric actuator can excite odd order and even order torsional vibrations through different excita-ion methods,and has the characteristics of simple structure,compactness,easy processing and installation.In order to verify thecorrectness of the design scheme,operating principle of the proposed torsional piezoelectric actuator,a theoretical model is estab-lished,and the dynamic characteristics are simulated and analyzed by using the finite element method.Finally,the vibration characteristics and dynamic behavior of the principle prototype are measured.The results show that the theoretical model calculation re-ults,the finite element simulation results and the experimental results are basically consistent,verifying the feasibility of the de-sign scheme of the proposed piezoelectric actuator and the corectness of its operating principle.