A reverse phase high performance liquid chromatographic method was established for the determination of salicylic acid by using ionic liquids as mobile phase additives.The chromatographic separation of salicylic acid was performed on a ZORBAX ODS column（250 mm×4.6 mm id，5 μm）.The detection of salicylic acid was carried out by ultraviolet（UV） detection.The effects of detection wavelength，pH value，concentration and alkyl chain length of ionic liquids on the separation and determination of salicylic acid were investigated.The optimum chromatographic conditions were as follows:mobile phase:methanol-30 mmol?L-1 1 butyl 3 methylimidazolium tetrafluoroborate aqueous solution（pH 3.0,adjusted with acetic acid） （60∶40，by volume），UV detection wavelength:300 nm，flow rate:10 mL?min-1，column temperature:30 ℃.Under the optimal conditions，the retention time of salicylic acid was about 4.4 min.The calibration curve showed a good linearity over the range of 2-100 mg?L-1 for salicylic acid with a correlation coefficient of 0.999 9.The detection limit was 0.059 mg/L.The average spiked recovery was 100% with relative standard deviation of 0.11%.The method was successfully applied in the determination of the content of salicylic acid in the pharmaceutical of Zujunqing Tinctura.