As a phyllosilicate, illite could fix K⁺ within interlayers. Thus K-Ar, Ar-Ar and Rb-Sr dating methods could be used to investigate and constrain the ages of different geologic events accompanying the formation of authigenic illite. Currently, it is significant to utilize authigenic illite to study the thermal evolution history of sedimentary basins, hydrothermal activities, tectonic movements, and hydrocarbon migration. This paper discusses the possibility of dating formation ages of evaporites by using isotope dating of illites from potash deposits. Although most studies showed that the formation of authigenic illite is favoured in high temperature environment, some authigenic illites could be formed in the salt lake environment of surface temperature. In this case, the controlling factor of the formation of illite is fluid composition. It is the theoretical basis for the study of evaporite formation age by using isotope chronology of authigenic illite. However, many challenges remain in practical research, requiring further investigation.