A multi-channel and high-speed FBG demodulator based STM32 is designed in this paper. The wavelength detection accuracy is improved using a difference of Gaussian (DoG) peak detection algorithm. The 16-channel FBG wavelengths are demodulated simultaneously and that the demodulation frequency can reach 1kHz. The experimental results show that the temperature sensitivity is 13.17 pm/ ºC. And meanwhile, the standard deviation and the average error of the FBG wavelength demodulated at the same temperature is 1.9 pm and 2.1 pm respectively.