To address the shortcomings of the current cutter wear detection methods which have difficulty to detect in real time, a new method based on the fiber Bragg grating (FBG) array for cutter wear detection is proposed. A multi-channel FBG wear detection system is built experimentally. By analyzing the positioning and wavelength division multiplexing capabilities of FBG, an embedded optical fiber sensor which can be used in cutter wear detection field is obtained. Four FBG arrays with 3 mm grating length are arranged separately with equal interval and demodulated simultaneously. The online real-time monitoring of wear length is realized, and the wear detection error is less than 0.23 mm.