The mechanism of the reduction of tapping torque by low-frequency torsional vibration tapping is analyzed. The experiments are carried out to compare the tapping torque and the service life of vibration tapping with that of continuous tapping without cutting fl uid. And the effect of cutting fl uids on vibration tapping is studied by experiments, too. It is indicated that not only the tapping torque could be reduced greatly, but also the service life of tap is extended remarkable by vibration tapping.