Abstract: In the soft-hard composite stratum, shield tunnelling may easily induce such problems as eccentric wear and fracture of disc cutters, so that the replacement frequency of cutter tools may increase largely. Therefore,considering the interaction between the disc cutter and strata based on RBD (rigid body dynamics)-DEM coupling method, the EDEM discrete element software is adopted to realize the passive motion of disc cutters in numerical simulation. Six working conditions with intersection angles of 15°, 30°, 45°, 60°, 75° and 90° are established to study the effect of changing penetration angles on impact of disc cutters in the soft-hard composite stratum. The results indicate that the penetration angle mainly affects the normal load on the tangential and normal planes. When the penetration angle is up to 45°, the peak load on the tangential and normal planes of the disc cutters might reach the maximum in the impact phase. When the penetration angle changes from 90° to 45°, the increase amplitude of peak normal load on normal and tangential planes might reach 18.74 times and 3.53 times, respectively. The abrupt change of normal load on normal plane is the main cause of falling off, offset and fracture of the disc cutter.