Abstract: At present，the lithium extraction from the brine of salt lakes has dominated the lithium production and its processes can be divided into three main steps，i.e.1) preparation of brine with high concentration of Li；2)separation of Li from Mg rich brines；and 3)precipitation of lithium carbonate.In which the second step is the most important. Current separation processes mainly use four different methods：natural separation，carbonate precipitation，roasting-leaching separation，and ion exchange-adsorption process.The principles and industrial applications of these four methods have been compared and analyzed in detail，and their application scope as well as the common method for sectionally removing magnesium from high magnesium-lithium ratio brine was also discussed.It was expected that this study can be used as a technical reference for the selection of proper process in the development of salt lake lithium resources of China.

Key words: salt lake brine, lithium extraction technology, separation of lithium from magnesium, magnesium lithium ratio