A new interrogation scheme based on semiconductor optical amplifier (SOA) ring laser and tunable Fabry-Perot (F-P) interferometer for fiber Bragg grating (FBG) sensing system is proposed. In the interrogation scheme, a gas absorption spectral line is used as a wavelength reference, and a comb filter is designed as a standard device that can dynamically calibrate the wavelength of FBG sensors. With digital signal processing technology and wavelength detection algorithm based on the 3 dB-power point, more than 1000 temperature sensors or 240 strain sensors can be interrogated with frequency of 1000 Hz. Experiment demonstrates that the strain measuring accuracy and wavelength resolution can reach to 0.6 με and 0.5 pm, respectively, and the temperature measuring precision can reach to 0.05 ℃.