Based on electromagnetic theory and vibration theory, the working principle of the magnetostrictive power ultrasonic transducer is analyzed. The nonlinear dynamic characteristics of the giant magnetostrictive material (GMM) in the outside magnetic field acts are studied, the wave equation of Terfenol D rod is deduced, and the steady-state solution to the wave equation is obta in ed. MATLAB 7.0 softwore is adopted to realize the simulation of the theoretical analysis results and the experimental verifying is also carried out.