The invention relates to a composite material impact crack detection algorithm based on fiber bragg grating sensing, and belongs to the technical field of structural health detection of composite materials. The method comprises the following steps: S1, embedding and curing a fiber grating sensor into a composite material, and carrying out an impact experiment on the composite material; S2, collecting the spectral data of the fiber grating sensor of the impact experiment; S3, calculating the wavelength gradient variation of the reflection spectrum of the fiber grating sensor; S4, carrying out real-time photographing and sampling on the composite material impact sample by the high-definition digital camera; and S5, judging and identifying the crack condition and the like of the composite material according to the high-definition digital camera. According to the composite material impact crack detection algorithm based on fiber bragg grating sensing, the generation of composite material impact cracks is determined by utilizing the wavelength gradient variation, the density of the impact cracks is judged through the normalized expansion width of the reflection spectrum of the fiber bragg grating sensor, and the recognition rate and the calculation efficiency are relatively high.