Optical spectrum analyzer (OSA) can achieve the higher precision and sensitivity, but it is disadvantageous for translating optical signal into electrical signal. A fiber Bragg grating (FBG) matched filtering system based on equi-intensity cantilever beam was presented in this paper. Strain characteristics in different location of cantilever beam were described, and the strain sensitivity of matching grating demodulation based on equi-intensity cantilever beam was deduced mathematically. Strain characteristics of cantilever beam were verified, and the sensing effect of the system was tested. The Bragg wavelength shift range of the demodulating FBG placed on the cantilever beam reached 10 nm, and scanning velocity was 0.125 nm/s. The system could demodulate slow-altered sensing signal accurately and rapidly.