Abstract To solve the impedance mismatch problem between the piezoelectric wafer and the tested material when ultrasonic testing is used to detect the internal defects of materials, alumina powder and epoxy resin are compounded to prepare the matching layer material. Then the matching layer of the ultrasonic transducer is designed according to the quarter wavelength theory. The pulse-echo signal of the developed matching layer is tested and analyzed. The results show that the sound velocity of the matching layer is consistent with the changing trend of the acoustic impedance. That is, the acoustic impedance increases with the increase of the alumina mass fraction, and the density is 1080.73kg/m³. The ultrasonic transducer was designed by matching layer with a sound velocity of 1059.49m/s, with an acoustic impedance of 1.14mryal and acoustic attenuation coefficient of 0.1279dB/mm has good bandwidth and sensitivity.