Abstract: In this paper，it establishes a new method of extracting and separating Rhodamine B solution by the aqueous two-phase system which formed by the hydrophilic ionic liquid BmimCl and K₂HPO₄.It also analyzes the influence factors of salt concentration，dye solution concentration，pH value and temperature on extraction rate.The result shows that when the ionic liquid volume is 500μL，the amount of salt is 6.0 g，in the acidic or neutral solution，the extraction rate of BmimCl-K₂HPO₄aqueous two-phase system to 70μg／m l Rhodamine B solutions will reach more than 95%.Beyond that，in the same conditions，this aqueous two-phase system has better extraction rate and extraction capacity to malachite green solution，methylene blue solution and methyl orange solution all.