Abstract: A piezoelectric planar transducer with high sensitivity is designed and fabricated.The transducer sensing element is an improvement of the 1-3-2 type piezoelectric composite structure.The piezoelectric ceramic column array with a substrate is not injected with polymer,and the upper surface is directly covered with a metal plate,then the structure of "piezoelectric column array with substrate+ metal cover plate" sensitive element(called "Air filled"sensitive element) is formed.The resonant frequency of the "Air filled" sensor is calculated theoretically and simulated by finite element method,which is in good agreement with the measured results.In order to compare the performances,the transducer with the structure of "1-3-2 type piezoelectric composite+metal cover plate,"(called "Polymer filled"transducer) is made.The effective electromechanical coupling coefficient,transmitting voltage response and receiving sensitivity of "Air filled" and "Polymer filled" sensor transducers are simulated and measured respectively.The "Air filled" transducer has a higher receiving sensitivity,which can be increased by 21 dB compared with the "Polymer filled"transducer.The transducer can effectively improve the sensitivity,which can provide a reference for the development of high-sensitivity transducer.