The severe safety hazards in buildings pose significant threats to personal and property safety. To effectively protect personal and property safety, the article proposes an optical fiber FP cavity displacement sensor with a dual-ring concave mirror structure for safety inspection. First, hydrofluoric acid is used for chemical etching to obtain a groove structure. Then, photoresist is used to create waveguides at the core position of the fiber. The fabricated fiber structure is then coated with a silver film using magnetron sputtering. Finally, the waveguide structure is washed away to obtain a double-ring concave mirror structure. Two fibers with the same structure form a Fabry-Perot cavity structure. The research results indicate that the dual-ring concave mirror structure can effectively enhance the sensitivity and linearity of the sensor. The designed sensor achieves a sensitivity of 105.535/μm within a range of 0-30 micrometers, with a linearity exceeding 0.999.