Electro-acoustical transducers are the popular elements for sonar array. The issue is to design a impedance matched transducer to interface the high power electric driving system for high power transmitting capability. The PC-base impedance measurement system is developed to measure the impedance of the Electro-acoustical transducer. Then the transducer of the simplify electrical equivalent circuit is discussed, and a method for determining element values at or near resonance is described. Meanwhile a PC-base impedance measurement system is developed to estimate the elements value of transducer's lump circuit model. An example illustrates the application of the method in the design of a matching transformer for a high power acoustical transmitter.