Abstract: In this paper a transformation net matrix is used to represent the characterastics of each vibrational part of a transducer, and the in herent relationship between mechnical quantities （velocity and force） and electrical quantites （voltage and current） is determined. Since matrix coefficients are the function of kl （k is wavenumber and l is the length of each part） after adjusting the length in proportion to frequency while keeping kl to be a constant the produced new transducer will reserve all the characterastics of the original reference transducer. Its changed performance parameters can be obtained by using a conversion proportional factor. Thus this paper offeres a convinient method and corresponding theoretical base for designing longitudinal vibration transducer. At the end a practical example using a general purpose design program is tested.