To address the challenge of quickly tuning the resonance frequency of ultrasonic transducers in real-time after manufacturing, this paper proposes integrating Terfenol-D into the horn of a piezoelectric ultrasonic transducer. In practical applications, the transducer is mechanically excited by a piezoelectric vibrator connected to an alternating current power supply, while the Terfenol-D is surrounded by a coil connected to a direct current power supply. By utilizing the delta-E (ΔE) effect of Terfenol-D, the modulus of the material changes in response to variations in the surrounding magnetic field, enabling real-time online adjustment of the resonance frequency. The resonance frequency and amplification coefficient of the transducer were analyzed using the transfer matrix method. Then, an impedance analyzer was employed to measure changes in the transducer's impedance and resonance frequency under different electric currents. Experimental results demonstrate that the resonance frequency of the transducer increases with increasing electric current. The developed piezoelectric ultrasonic transducer, featuring Terfenol-D embedded in the horn, achieves rapid and real-time resonance frequency adjustment within a specific range. This innovation provides a novel solution for complex ultrasonic application scenarios requiring frequent transducer replacements.