Ionic liquids(ILs) are currently developing mohen salts with melting points below 100 ℃ and arousing considerable scientific interest in various disciplines.Due to their miscibility with water and high conductivity, ILs are used as either supporting electrolytes or additives in mobile phase in CE.In our study, dioxopromethazine enantiomers were separated by capillary electrophoresis, using ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate([bmim]BF4) as a modifier to improve the resolution(Rs), β-cyclodextrin as a chiral selector, phosphate as a electrolyte.The effects of several parameters on the resolution of dioxopromethazine enantiomers were investigated.