According to the mechanism of defects in CFRP drilling process, the acoustic emission signal rms value during drilling is collected by acoustic emission sensor. The RMS under different drilling parameters are analyzed, and the RMS corresponding to the tear at the entrance and the exit of the hole are identified. The experimental results show that the tear at the entrance and the exit can cause the mutation of the RMS during the drilling process, and can be effectively identified. When the spindle speed is constant, the RMS increases with the increase of the feed rate. When the amount is constant, RMS increases with the increase of spindle speed.