Lithium isotopes are effective tracers of geochemical processes due to their large relative mass difference and therefore fractionation degree, especially in the surface environment. This study attempts to introduce the basic properties of lithium and discuss the knowledge of lithium isotope fractionation behaviors,and the controversy involved in the surface environment. Moreover,as the geochemical response of tectonic activities and climate change events, the lithium isotopic characteristics in the surface environment reflecting regional tectonics, climatic change, and the degree of continental weathering have the potential to be a quantitative index for calculating the CO_2 consumption of continental weathering. In addition,lithium isotopes in salinology are mainly used to trace source material; however, they should be combined with other tracer elements to jointly probe the source of lithium resources and prospect problems. Nevertheless,whether the isotopic compositions of salt lake sediments or brine can be utilized to quantitatively calculate the CO_2 consumption of continental weathering processes, and lay the foundation for a global carbon sink and the related paleo-climate and paleo-environment, requires further investigation and verification.