At present, roadway roof deformation monitoring method adopts on-line real-time monitoring based on underground industrial ring network, electronic and fiber Bragg grating displacement sensors which are connected by wireless means, has many blind spots, large errors, and relies on continuous power supply. For the above problems, coal mine roadway roof monitoring system based on distributed optical fiber technology was designed. The system uses Brillouin optical time domain reflectometer (BOTDR) as the core monitoring tool for data collection and analysis. It uses 5 mm stranded steal optical fiber as sensing fiber, and uses anchor rod and anchor cable as fixed points to lay optical cable. The strain of the optical fiber is used to monitor deformation of the roof, and the real-time online distributed monitoring of the roof of the coal mine roadway is realized. Field application results show that the fiber strain change can accurately reflect roof deformation in real time,the roof monitoring results based on fiber strain are consistent with the monitoring results of the roof delamination instrument and the cross method. Using fiber optic strain to characterize roof deformation eliminates human factors and power outages, and ensures objectivity of the monitoring results. The power-free distributed optical fiber strain monitoring method with long-distance, good corrosion-resistant and anti-interference performance provides a new way of roadway monitoring for coal mine.