Abstract: For the problem of stick-slip vibration caused by hard rock formation in the process of drill bit penetrating in coal mine, and the discrete element method (DEM) was employed to study the rock cutting performance and stick-slip vibration behavior of PDC bit drilling in five typical different hardness rock strata. The result shows that the stick-slip phenomenon of the bit is more obvious with the increasing of the formation hardness, and in the ultra-hard rock layer, it slips on the rock surface and cannot be effectively drilled. The approach of increasing the rotational speed of the bit can weaken the stick-slip behavior to an extent, but it has no obvious effect on improving the drilling efficiency. The drilling performance of the bit can be improved by increasing drilling pressure, but it will also lead to more serious stick-slip vibration. The torsional impact method can effectively weaken or even inhibit the stick-slip vibration of the bit and improve the drilling performance. However, excessive torsional impact force will lead to an increase in the impact load on the bit.