To improve the accuracy of demodulation system of fiber Bragg grating (FBG) sensors,a demodulation method of FBG center wavelength based on a fiber comb filter is proposed. A constant temperature channel of the demodulation system is connected with a fiber comb filter,which offers reference points to calibrate the center wavelength of FBG. The under-bit machine collects and processes the photoelectric signal voltage transformed to rectangular voltage pulse. The computer displays dynamically the FBG wavelength demodulation process and calibrates the Bragg grating center wavelength. The experimental results show that,compared with other wavelength demodulators,it has many advantages,such as flexibility,stabilization,easy maintenance,high-speed,high-precision,and so on. The wavelength demodulation system can be used extensively in large-scale multipoint monitor engineering.