In this paper,we propose to use two Fabry-Perot(F-P)cavities as the double-edged filters to achieve the wavelength demodulation in Fiber Bragg Grating(FBG)sensor system.Since the reflected FBG signal through the two filters have different spectral characteristics and light intensities,the ratio of two intensities can be used to determine the wavelength of the measured light.Through the calculation and simulation,the system can realize the demodulation of the sensing FBG signal.The simulation results show th...