Abstract: X-ray Photoelectron Spectroscopy (XPS) is one of most popular surface analysis methods, it plays an important role in the studies of tribochemistry, friction and wear mechanisms, and failure of tribological materials. This paper outlineed fundamental principle, structure and analysis characteristics of XPS; reviewed the application of XPS in the tribology fields, such as in adsorption and reaction of lubricating oil additives, polymer fillers, gas-phase lubrication and ionic liquids, and inspired the manifold applications of XPS in the tribological studies.