Abstract: The deposit brine of potash production from Indochina Peninsula rock salt mine has a bromine ion mass concentration of 2000—3000 mg/L, making it a valuable raw material for bromine production. Effective use of bromine resources associated with rock salt mines is important for improving the comprehensive utilization of rock salt mines. In this paper, a capillary microchannel set-up was built to carry out the research on the separation of bromine from the simulated deposit brine. By combining quantum chemical calculations and extraction experiments, n-dodecane was selected as the extractant for bromine because of its decent extraction ratio and relatively low bromine loss ratio. Orthogonal experimental design was used to determine the optimal process conditions for the microextraction. The bromine extraction rate was greater than 80%, at the condition of temperature 20 ℃, oil-water phase volume ratio 1.0, T-type mixer inner through hole diameter 0.25 mm, capillary microchannel inner diameter 0.5 mm, total flow rate 0.10 mL/min, and residence time 70 s.