Abstract: A piezoelectric transducer consisted of n elements is desctribed by one dimensional theory.By means of transfer matrix operations,a computer program has been made for calculating the resonant frequencies of transducer and distribution of displacement along its axis.It is shown that a maximum ratio of the amplitude at the radiating surface to that at the backing of transducer can be obtained under an optimum length radio of transducer L₅/(L₃+L₄).Theoretical results are compared with measured ones,the two agree fairly well.