In this paper, hydrochemical characteristics and origin of saline springs/brines in southwestern and northern Tarim Basin were studied, ionic ratios were discussed, and a corresponding indicator system was suggested for potassium exploration. Analytical data of 194 saline spring/brine samples were obtained from both field survey and geochemical materials available. It is found that saline springs/brines in southwestern Tarim Basin (Shache Basin, a sub-basin) mainly belong to the sulfate type, with a few belonging to the chloride type, while in northern Tarim Basin (Kuqa Basin, a sub-basin), the chloride type is dominant, followed by the sulfate type. Evolution processes of saline springs/brines in this area are very complicated, consisting of recharge from the depth of the earth, water-rock salt interaction, inflow of surface water and strong evaporation. As for potassium exploration, the potassium-to-chloride ratio, the magnesium-to-chloride ratio, the sodium-to-chloride ratio and the boron-to-chloride ratio can well serve as indicators for potassium deposit prediction instead of the bromine-to-chloride ratio and the potassium-to-bromine ratio, due to the paucity of bromine in the basin. The determination of environmental background values for chemical components, TDS and ionic ratios can provide useful information and references for potassium exploration in the Tarim Basin as well as in other saline basins of China.