Abstract: Qarhan Salt Lake is the largest K-Mg salt deposit with proven reserves in China.The formation of K-Mg salt deposit is controlled by several factors: strata and magmatite material components of surrounding mountain area,the mountain-building and basin-formation movement caused by Qinghai-Tibet Plateau movement,paleoclimate and paleoenvironment,and other factors.Promising K-Mg salt deposit is mainly distributed in Quaternary stratum.