Fiber Bragg gratings (FBGs) are widely used as sensors for temperature, strain, and vibration measurement. Their most important advantage is signal modulation consisting in shifting the spectrum in the wavelength domain. Determining the wavelength shift is the most important issue in precise measurements of. This paper introduces the design principle of high-speed optical fiber grating demodulator based on scanning laser source, elaborated on high-speed fiber Bragg grating demodulation system principle. By changing the step size of each calculation.