The invention discloses a two-frequency ultrasonic transducer. The two-frequency ultrasonic transducer comprises a back lining, an ultrasonic emission layer, a matching layer, an ultrasonic receivinglayer and a protecting layer, wherein the back lining and the ultrasonic emission layer are adhered through ultrasonic transducer adhering glue, the ultrasonic emission layer and the matching layer are adhered through ultrasonic transducer adhering glue, the matching layer and the ultrasonic receiving layer are adhered through ultrasonic transducer adhering glue, and the ultrasonic receiving layerand the protecting layer are adhered through ultrasonic transducer adhering glue; two electrodes are guided from the ultrasonic emission layer and the matching layer to be supplied for the emission work of the ultrasonic transducer; two electrodes are guided from the ultrasonic receiving layer and the matching layer to be supplied for the receiving work of the ultrasonic transducer; and the material of the ultrasonic emission layer is lead magnesium niobate-lead titanate (PMN-PT), and the material of the ultrasonic receiving layer is polyvinylidene fluoride(PVDF). According to the two-frequency ultrasonic transducer disclosed by the invention, two piezoelectric materials, namely PMN-PT and PVDF, are used in the same transducer, and the characteristic that the acoustic impedance of the PVDF material is close to that of human body tissue is used, so that better matching is easy to obtain, besides, the capacitivity is low, the PVDF material is also easy to be matched with an electric output loop, and during receiving, few tail waves exist; and harmonic wave imaging of 20-35M is adopted, so that the imaging resolution is higher.