The invention discloses a stope overlying rock separation layer monitoring method based on optical fiber, and belongs to the field of soil environment monitoring. The stope overlying rock separation layer monitoring method based on the optical fiber comprises the steps that firstly, the development range of an overlying rock separation layer is predicted; secondly, the development size of the overlying rock separation layer is predicted; thirdly, five fixed point optical fibers are adopted, and the concrete schemes of stope overlying rock separation layer monitoring based on 'dichotomy' is designed; fourthly, customization and burying of the fixed point optical fiber are conducted; fifthly, movement of overlying rock separation layer is monitored; and sixthly, the inspecting result is analyzed, and the development position, size and regulation of the overlying rock separation layer are obtained. According to the stope overlying rock separation layer monitoring method based on the optical fiber, the stope overlying rock separation layer monitoring method is based on an optical fiber technology, the optical fiber is a sensing original copy and a transmission original copy, the tensile deformation of the separation layer can be monitored, compressed deformation of the separation layer can further be monitored, the expansion-closing-stabilizing development processes of the separation layer are researched advantageously, five fixed point optical fibers designed based on the'dichotomy' are adopted, the development position and volume of the overlying rock separation layer can beaccurately determined, slip casting and sinking-reduction of the separation layer are conducted advantageously, ground sinking is avoided, and the soil environment is protected.