Abstract: Aiming at the defects of high energy consumption, susceptibility to electromagnetic interference, high cost and difficulty in laying of existing security sensor systems, a smart optical fiber sensor security alarm system with low energy consumption, high sensitivity and no electromagnetic interference is proposed. The system sensor adopts a microbent-type step fiber structure. Based on the analysis of the relationship between the optical energy loss of the microbent fiber sensor and the relative refractive index difference function of the resonant frequency, the structural parameters of the sensing unit are optimized. The experiment first tested the interference suppression algorithm. From the waveform distribution, it can be seen that the noise is greatly suppressed after using this algorithm. On this basis, the system was used to test the interference of different pseudotargets. A 650.0 nm laser with a power of 2.5 mW, a fiber power meter, a microbend fiber holder and a microbend fiber sensor with a core of 9 μm were selected to build a fiber microbend sensing experiment, and the photoelectric response characteristics of 4 different security states were determined. analyse. The results show that as long as the corresponding signal analysis methods are adopted for different interference types, the probability of system misrecognition can be effectively reduced. It can be seen that the optical fiber microbend sensing system has the advantages of high sensitivity, low energy consumption, anti-interference, etc., and meets the design requirements. It has good application prospects in the field of intelligent security.