Abstract: A fault detection system of mine wire rope based on tunnel magneto-resistance (TMR) sensor is designed, and the system excitation device, hardware circuit and software implementation are described. Then, experimental platform was set up and a ψ16 mm-19×7+IWR oily steel wire rope with five different degrees of broken wire defects on the surface was on-line tested. The experimental results show that the system has the advantages of high sensitivity, good temperature stability, high signal-to-noise ratio and small size. The minimum detection accuracy is a single broken wire defect with a loss of 0.4% of the metal section and the axial minimum resolution is 5 mm, which fully meets the requirements of practical engineering application.