Membrane is a raising technology for selective metal mining from brine that could be used for lithium extraction. Selective and efficient ultrasonic assisted separation of lithium from brine containing alkali metals salts is conducted using composite membrane formed by sealing supported ionic liquid membrane (1-alkyl-3-methylimidazolium hexafluorophosphate ([RMIM][PF6]) + tributyl phosphate (TBP) in polyvinylidene fluoride (PVDF)) with polyvinyl chloride (PVC) thin film membrane. This process is examined by adjusting of parameters of membrane, feed, and ultrasonic to reveal the best condition for selective separation of lithium from alkali metals. Results show that membrane containing 0.5:0.5 mass fraction of [MOIM][PF6]:TBP is more selective between the studied membranes. The flux of lithium is higher during short sonication times, while it decreases with increment of the duration of ultrasonic irradiation. At 100 kHz, 50 % amplitude and sonication sequence with a feed phase concentration containing 500 ppm of chlorine slats of Li, Na, and K in the presence of different concentration of ILM, flux of Li was 10.45 mg cm−2 min−1 Pa−1 with selectivity indexes of 2.21 Li:Na and 2.49 Li:K.