A new finishing technology of the swirling air flow compounded with magnetic-field is advanced. Force acting on abrasive is analyzed by the action of airstream and magnetic-field coupling according to gas-solid particles two-phase flow. Finishing mechanism on the swirling air flow compounded with magnetic-field is illustrated, namely, burrs and microcosmic peak on the surface of workpiece are broken, grinded and cut via a great deal of abrasive particle impacting, microchipping and rolling machined surface. Unthreaded hole is experimented on the condition of changing magnetic induction intensity B and machining time t. Changing curve of surface roughness Ra along with time t is shown. Research indicates that machining time of the swirling air flow compounded with magnetic-field is short and machining efficiency is high. The longer machining time is, the smaller surface roughness Ra is and the better machining effect is.