Abstract: One hundred years ago, Laue discovered the remarkable phenomenon of X-ray diffraction in a CuSO4 ·5H2O crystal, which gave rise to the new era of crystal structure determination based on X-ray diffraction. Over the past 100 years, this has played an important role in natural science, medicine, archeology, history and many other fields. This paper reviews the history of the discovery of X-ray diffraction, the fundamentals of kinematical and dynamical X-ray diffraction theory, as well as various specific applications in the study of polycrystalline powders, single crystals, artificial functional crystals, and thin film materials. Future prospects for the development of X-ray diffraction technology are briefly mentioned.