In this paper, a scheme for a fiber Bragg grating sensor system in guarding against burglary is put forward. And axial strain sensitivity of the fiber grating against the optical power of reflection and refraction is analyzed. By designing the parameters of the fiber grating and the strain sensing device and choosing the wavelength of the laser, we design a sensing system that can sense the axial strain of the fiber grating. This system has reference value for the application of the Internet of things.