Abstract: The salt lake brine in Tibetan Plateau has a rich lithium reserves.After the process of evaporation in the salt pan， the most impurities，such as Na⁺，K⁺，SO₄^2-，Cl^-，and Mg²⁺ in the brine can be removed.At the same time，the ratio of Mg/Li is decreased to the range of 8~12 and the mass fraction of lithium ion can be concentrated to over 0.5%.The magnesium ions in the evaporated lithium-rich brine are precipitated with the sodium carbonate and sodium hydroxide as precipitators，and then the lithium is extracted with sodium carbonate as precipitator.After a series of experiments in all the stages of the process，coarse lithium carbonate with relatively higher purity and yield is finally obtained.

Key words: saline lake brine, extraction process of lithium, precipitation method, lithium carbonate