Electron spectrometer is an instrument that uses photoelectric effect to measure the relationship between the kinetic energy of photoelectrons and their quantity, so as to judge the content of various elements on the surface of the sample. The electron spectrometer can analyze all elements in solid, liquid, and gas samples except hydrogen. It can also study the state of atoms, the conditions around atoms and the molecular structure. It is used in surface chemical analysis, molecular structure, catalysts, new materials, etc. It has been applied in the research field.