The piezoelectric ultrasonic transducer has different input impedances at different frequencies. The mismatch between the output impedance of the driving signal source and the input impedance of the transducer will result in energy losses and can’t meedt the power requirements of the transducer, thus the spectroscopy diffraction efficiency will be reduced and affect the spectral imaging quality. So to do this, the transducer impedance frequency characteristics has been studied deeply and a new broadband impedance matching network was designed. By ADS simulation and experimental testing of matching circuit, Finally, the spectral diffraction efficiency get up to 70% within the 115～180 MHz ultrasonic frequency.