The present invention relates to a cutting device for cutting the insulation layer of an electric wire. The device is characterized by comprising a clamping part, a cutting part and a detection part. The clamping part comprises a clamping piece, a spring and a pressing rod, wherein the pressing rod, the spring and the clamping piece are sequentially connected. The cutting part is provided with a channel and a cutting knife. When not in use, the cutting knife is outside the region of the channel. The detection part is provided with a clamping piece, a spring, a pressing rod, a detection piece and a detector. The detection piece is arranged at one end of the clamping piece. The two ends of the detector are respectively connected with the cutting knife and the detection piece. The detector is arranged in the detection part. The cutting part can be rotated around an axis B-B relative to the clamping part. The detection part can be rotated around the axis B-B relative to the cutting part. By adopting the stripping device for stripping the insulation layer of the electric wire, the workload of manually stripping the insulation layer of the electric wire is reduced, while the quality of the electrical wire after the insulation layer of the electric wire is stripped is improved at the same time.