A distributed optical fiber sensing system composed of communication optical cables, strain optical cables, and a Brillouin optical time-domain reflectometer is adopted to conduct long-term monitoring of the slope stability of open-pit mines. By optimizing the trench structure design, anchoring system, and optical cable laying path, the optical cable deployment for 10 km, 3300 m, and 3500 m of the open-pit mine slope is completed, establishing a distributed monitoring engineering verification system for open-pit mine slopes. The research results show that through reasonable engineering design and control of the test parameters of the Brillouin optical time-domain reflectometer, long-distance, continuous, real-time, and large-scale distributed monitoring can be achieved; rock and soil masses, anchor rods, and strain optical cables can achieve a better coupling effect, which can realize the spatial?temporal continuous perception of surface and internal deformation of open-pit mine slopes. This method provides valuable insights into the deformation behavior of rock and soil mass slopes. In the future, by combining this monitoring technology with methods such as numerical simulation, potential landslide risks can be effectively and timely identified, and necessary measures can be implemented to ensure the stability of the slope.