According to the defects in the process of drilling carbon fiber reinforced plastic, the drilling experiment was carried out by self-designed bit-step drill. The drilling force, hole outlet quality and hole wall surface roughness of step drill drilling carbon fiber reinforced plastic under different cutting parameters were studied and were compared with twist drill. The experimental results show that the drilling axial force produced by stepped drill is about 1/2 of the axial force produced by twist drill, the surface roughness of hole wall is smaller, and the hole exit has no obvious defects. Step drill is suitable for drilling carbon fiber reinforced plastic.