A demodulation system based on 256 pixels linear array InGaAs detector for fiber Bragg grating sensors was researched and realized. Based on the linear array InGaAs detector, the peak positioning principle of the fiber Bragg grating reflection spectrum was put forward. This multiple FBG spectrum parallel processing could be realized. The demodulation quantity of single channel depended on the bandwidth of the FBG sensor and the center wavelength drift range. Based on the spectral data of 256 pixels, Gaussian curve model for central wavelength was adopted. By setting the threshold value, the number of reflection spectrum peak was obtained, separately for each spectrum peak fitting. The demodulation technique was proved to be highly accurate and highly stable by the experiment results. The stability of peak searching algorithm reached ±0.5 pm. The demodulation method has no mechanical moving parts, which realizes the parallel processing and quick response of the fiber Bragg grating center wavelength. The wavelength demodulation range is 1 525-1 570 nm. It provides a high-speed demodulation scheme for fiber Bragg grating sensing.