In this study a suitable alcohol/salt aqueous two-phase (ATP) system was selected for the recovery of lactic acid from an aqueous solution. From the different ATP systems studied, the ethanol/dipotassium hydrogen phosphate ATP system appeared to be favorable. To examine the potential of this ATP system, the extraction yield of lactic acid in aqueous solutions was optimized with the response surface methodology. The parameters studied were concentrations of ethanol (22.00-38.80%, w/w), dipotassium hydrogen phosphate (15.00-31.80%, w/w) and lactic acid (26.36-93.64g/L). The optimum conditions were found to be 30.23% w/w ethanol, 18.40% w/w dipotassium hydrogen phosphate, and 80g/L lactic acid. Under these conditions, a favorable extraction yield of lactic acid was obtained. The maximum partition coefficient of lactic acid and extraction yield was determined as 2.26 and 87%, respectively. The optimum extraction conditions were then used to guide the recovery of lactic acid from a real fermentation broth. As a result, the partition coefficient and extraction yield of lactic acid reached 2.06-80%, respectively.