Effect of 1-butyl-3-methylimidazolium tetrafluoroborate （［BMIM］BF4）on the chromatographic behavior of glycyrrhizin（GL） and its derivatives was studied by adding ionic liquids in mobible phase of reverse phase high performance liquid chromatography（HPLC）.The result showed that the addition of ILs had a superior effect on the determination of GL,glycyrrhetinic acid（GA） and glycyrrhetinic acid monoglucuronide（GAMG） by improving chromatographic peak shape,reducing tailing,increasing peak area and peak height,and enhancing detection sensitivity.In addition，the simultaneous detection time of three substances was greatly shortened,and the detection efficiency was obviously improved.The optimum chromatographic conditions were as follows:separation column:InertSustain C18 （4.6 mm×250 mm i.d.，5 μm）;column temprerature:40 ℃;mobile phase:methanol -1.0 mmol/L ［BMIM］BF4 aqueous solution（81∶19,adjusted pH 3.0 with acetic acid）;flow rate:0.7 mL/min;injection volume:20 μL;detection wavelength:251 nm.The calibration curves showed good linearities over the concentration range of 5.00-100 mg/L for three compounds with correlation coefficients not less than 0.999 8.The detection limits （S/N=3） of GL,GA and GAMG were 0.02,0.04 and 0.09 mg/L,with spiked recoveries of 100.1%,98.0% and 98.2%,respectively.The relative standard deviations（RSD） were in the range of 0.18%-0.43%.The method was used to determine the above three components in GL bioconversion system with satisfactory result.