The mechanism of ultrasonic vibration honing Nd-Fe-B has been briefly elaborated after the introduction of the strategic significance of processing Nd-Fe-B. Based on the formation principle of Scanning Electrtmic Microscope (SEM), and at the examination with the aid of SEM to the ultrasonic vibration honing Nd-Fe-B material's superficial microscopic topography, the paper discusses the new processing nechanism according to the SEM examination picture. The research indicates that as a result of supersonic high frequency vibration, the path of the abrasion extends at the same time, and the supersonic cavitation effect forms the intense shock-wave, knpacting Nd-Fe-B material's intemal surface, providing the supersonic energy for the superticial abrasive dust's dimination, which directly explain that the honing processing efficiency is enhanced, and the processing surface roughness is high.