Abstract: Firstly, the X-ray, its interaction with substances and the basic theory of crystallography were briefly introduced. Then, the application of X-ray analysis technology in mechanical equipment failure analysis was introduced in detail, including X-ray flaw detection, X-ray diffraction analysis and X-ray photoelectron spectroscopy analysis. The analysis shows that X-ray analysis technology was widely used in the failure analysis of mechanical equipments. For its strong penetrability, the X-ray flaw detection can be used to detect various kinds of defects in materials, which can provide useful guidance for sampling and cutting of complex failure parts. X-ray diffraction can be used to analyze and study crystals from the atomic or ionic levels, and also to accurately determine the residual stresses that may cause failure of components. X-ray can make the irradiated material ionize and produce characteristic information for each element. Various spectrometers with X-ray as the light source can be used to analyze the chemical element compositions and element valence states of materials, which plays an important role in the accurate judgment of the failure causes.