Abstract: A nonlinear driving manner of Galfenol transducer is developed. The transducer can generate a sine wave without a biased magnetic field, by designing a complex electric signal to match the nonlinear magnetostrictive strain. Through theoretical analysis, a simple nonlinear signal at low magnetic field is found to drive the transducer, which is called semi-frequency drive mode, because that the signal frequency is half the frequency of the radiation. A Tonpilz transducer is designed and measured in pool driven by the semi-frequency drive mode. The results show that transducer driven by the semi-frequency dive mode can achieve a source level of 192 dB at 4.2 Amps. The experiment confirmed that nonlinear driving manner of Galfenol transducer is feasible. The nonlinear drive signal at high magnetic field is got through theoretical analysis and simulation.