A reversed-phase high performance liquid chromatographic method was developed for the determination of six aromatic carboxylic acids including p-amino benzoic acid,phthalic acid,p-hydroxy benzoic acid,salicylate acid,benzoic acid and o-methyl benzoic acid，by using ionic liquids as mobile phase additives.The chromatographic separation of aromatic carboxylic acids was performed on a RP-C18 column.The detection of aromatic carboxylic acids was carried out by ultraviolet(UV) detection.The comparison of three different mobile phases was performed.When the ionic liquids were chosen as mobile phase additives,the chromatogram was improved with better chromatographic peak shape and higher sensitivity.Effects of experimental conditions,e.g.detection wavelength,methanol content,pH value,concentrations and alkyl chain length of ionic liquids on separation and determination of aromatic carboxylic acids were investigated.The optimum chromatographic conditions were as follows：mobile phase：methanol-1.0 mmol/L 1-butyl-3-methylimidazolium tetrafluoroborate aqueous solution(pH 3.0)(40∶60),UV detection wavelength：240 nm,flow rate：1.0 mL/min,column temperature：30 ℃.The six aromatic carboxylic acids were successfully separated within 16.5 min under the optimal conditions.The calibration curves showed good linearities over the range of 5-120 mg/L for aromatic carboxylic acids with correlation coefficients more than 0.999.The average recoveries of spiked components were in the range of 98.3%-103.8%,with relative standard deviations not more than 0.63%.The method was successfully used to determine the content of aromatic carboxylic acids in pharmaceuticals,Compound Redbud Bark and Salicylic Acid solution and the Zujunqing Tinctura.