Abstract: Stick-slip vibration is a common phenomenon in the process of PDC drilling, and it can cause the premature failure and low drilling efficiency of PDC bit. And as a result, the drilling cost is increased. If a set of torsion impactor is installed at the top of the drill bit, it will apply a cyclic high-frequency circumferential impact load to the drill bit during the drilling, so that the torque accumulating time can be reduced and the stick-slip vibration in the process of PDC drilling can be mitigated. the behavior of PDC bit under the effect of circumferential torsion impactor in the process of drilling was analyzed. Then, combined with bit drilling mechanics analysis and rock fragmentation, the rock-breaking mechanical model of PDC bit under the effect of circumferential cyclic impact load was established. Its numerical simulation results show that under the effect of a certain torque impact, the pipe sticking time is reduced by 51% when internal cohesion of the drilled rock is 40 MPa. It is indicated that stick-slip vibration can be mitigated by applying the circumferential impact to PDC bit. The research results provide the theoretical support for the application of circumferential torsion impactor in the drilling process of PDC bit.