Piezoelectric underwater acoustic transducer is a kind of device for underwater detection working as not only an actuator but also a sensor.The technique of predicting acoustical characteristics of transducer is important to robust design of transducer in harsh underwater environment.Finite element methods are very powerful to characteristic analysis of transducers in different environments.Two dimensional axisymmetric finite element model of one type of Tonpilz transducer is generated and the dynamic analysis of it is conducted through a developing program based on finite element method.Some acoustic characteristics are obtained,and parts of them are compared with those from ANSYS.