Abstract: There are many advantages of 1-3 piezocomposite transducers, such as lighter weight, lower specific acoustic impedance. The matching layer is commonly used to expand the bandwidth of composite transducers. A 1-3 piezocomposite transducer is studied with thickness-mode oscillations model, lateral-mode model and finite element method. The finite element modal of transducer is set up with ANSYS software and the structure of the transducer is optimized. A fi- nal 1-3 piezocomposite transducer is designed, which used the thickness mode and the first lateral-mode. The bandwidth of the transducer is 190 ~ 390 kHz, in which the ripple of the transmitting voltage response does not exceed ±2 dB. There are several conclusions from the research: The bandwidth of 1-3 piezocomposite transducers can be expanded by the thickness mode and the first lateral-mode, and it gives a method to achieve the broad-band projecting performance of high-frequency transducer.