Abstract: X-ray powder diffractometer is widely used in material analysis, and most commonly used for phase analysis. This paper mainly introduces the principle of X-ray powder diffraction instrument, formation of diffraction pattern, composition of the instrument, method of operation, phase analysis and so on, also told us how to choose the condition of operation. On the other hand, this paper introduces some equipment maintenance experience and safety of instrument operation. It will make readers have an good understanding of X-ray powder diffractometer.