The scattering and identifying model of the wear particle is influenced by the nonlinear characteristic of the surrounding ultrasonic field of ultrasonic wear particle transducer.The nonlinear sound field of the ultrasonic wear particle transducer was modeled by using the KZK equation,the KZK equation was solved numerically by the finite difference time domain method,and the time domain and frequency domain characteristics were investigated.The results indicate that the focus position may deviate a little,the axial length of the focal spot is much larger than the radial length,the pressure waveform as well as the corresponding center frequency varies in the focus region,and the center frequency of the sound field is lower than that of the source signal.The experimental results validate the simulation conclusion.