Extreme ultraviolet (EUV) multilayer are crucial components of EUV lithography optical systems. During the operation of lithography systems, the performance of EUV multilayer mirrors can be affected significantly by surface contaminants, thus resulting in reduced light-source output power and decreased overall system lifespan. Understanding the contamination of EUV multilayer mirrors and developing targeted control technologies can enhance the stability and longevity of EUV lithography systems. This paper reviews the research progress on the contamination control of EUV multilayer mirrors, with emphasis on the causes of surface contamination and cleaning technologies. It provides a detailed overview of the main contaminants and formation mechanisms of multilayer mirrors in EUV lithography systems, as well as prevention, suppression, and cleaning techniques for different contamination types.