Based on EDM method combined with ultrasonic field, the effects of different electric current, impulse width, and voltage on the surface morphology of nickel microspheres were studied. The preparation condition and forming mechanism of microspheres with compact and smooth surface were investigated. The result shows that removal rate and explosion force of the electrode materials play an important role in forming microspheres, and homogeneous nucleation goes against the uniformity of the surface morphologies of microspheres.