Abstract: Aiming at the problems of low automation, difficult threshold adjustment and misjudgment caused by the interference of surrounding equipment, the magnetoresistance effect detection technology is applied to the start and stop detection of coal mine equipment for the first time through experimental demonstration, which can quantitatively detect the relationship between the current value and magnetic field value in the cable, and can be used to adjust the start/stop threshold of the sensor. Firstly, the magnetic field intensity at any position of the cable is deduced by modeling and simulation of three-core cable, and the distribution law of magnetic leakage field around the cable is analyzed theoretically. Secondly, experiments are designed to verify the relationship between the current value and the change of magnetic field at different positions, and a method of self-adjusting start/stop threshold is proposed. Then, the magnetic field shielding technology is studied, and the experimental results show that 06Cr13 stainless steel can effectively shield the external interference magnetic field. Finally, the reliability and anti-interference performance of the designed sensor are verified on site, which reduces the workload of on-site installation and debugging. In addition, the sensor can also be marked on and off by the upper computer/stop threshold.