The utility model discloses a high-speed fiber grating demodulation system, belonging to the technical field of fiber grating sensing and wavelength demodulation. The high-speed fiber grating demodulation system is mainly composed of an FPGA (Field Programmable Gate Array) demodulation circuit board, a reflection type diffraction grating spectrum demodulation module, an ASE (Amplified Spontaneous Emission) light source, a high-speed optical switch, an optical coupler, a switching power supply and a host computer, wherein the FPGA demodulation circuit board comprises an FPGA processor, a high-speed analog signal collecting circuit, a filter circuit, a network communication interface circuit, an SDRAM (Synchronous Dynamic Random Access Memory) storage circuit, an optical switch control circuit, and a power conversion and voltage stabilization circuit; the high-speed optical switch is connected with the ASE light source and the reflection type diffraction grating spectrum demodulation module via the optical coupler; the FPGA demodulation circuit board is connected with the reflection type diffraction grating spectrum demodulation module via a control interface; and original spectrum signals are collected and transmitted to the host computer via network cables, and software of the host computer demodulates the wavelength of the signals and displays relative data. The high-speed fiber grating demodulation system can improve the stability of circuits, effectively improve the demodulation speed, and overcome interference of light noises in wavelength modulation.