Abstract: Detecting winding line package of optical fiber by X-ray, through the analysis of traditional X-ray detected image, the feasibility of optical fibers winding flaws by X-ray detection was confirmed and giving the program of detection. The law of single-fiber ray attenuation is given through scanning. When the incident photon wavelength is 0.154 nm，the single fiber attenuation coefficient is 4.7/mm, the fibers attenuation cycle is axisymmetric distribution, and the attenuation of fiber center is not the biggest which is between fiber margin and centers. The result provided the theoretical and experimental basis for development of the diagnostic system.