A geothermal fluid has a high level of total dissolved solids originating from various geochemical reactions between the reservoir and the fracturing fluid. Approximately 150 ppm of lithium ions are contained in the geothermal fluid, which can be used in various industries. Thus, in this study, a combined method of precipitation and solvent extraction was implemented to separate lithium from the geothermal fluid containing various cations. Two precipitation steps were applied to remove the divalent and silicate ions (98.0%) and then lithium (87.7%) was successfully recovered using 1.5 M D2EHPA and 0.3 M TBP from the diluted geothermal fluid.