Abstract: Mercury isotope technology is an important means for the study of mercury biogeochemical cycle and pollution prevention and control and has wide applications in mercury source analysis and process tracing. However, due to the extremely low mercury content in the natural environment, environmental samples need to be pretreated by a series of rigorous methods for mercury isotope analysis. At present, wet digestion and combustion-trapping are two main pretreatment methods for solid samples, the pretreatment methods for liquid samples are mainly chromatographic separation and purge-and-trap. The gaseous samples are collected by various solid adsorbents before pretreatment with combustion-trapping method. The pretreatment methods for mercury analysis in various environmental media samples are summarized in this paper and the advantages and disadvantages of each method compared. In order to expand the application of mercury isotope technology in the study of mercury biogeochemical cycle, it is urgent to establish a faster and more efficient pretreatment technology.