A method was developed for the determination of ionic liquid anion of p-toluenesulfonate by ion chromatography with direct (non-suppressed) conductivity detection.Chromatographic separation was performed on a Shim-pack IC-A3 anion exchange column.The influences of mobile phase types and column temperature on retention time of p-toluenesulfonate were investigated.The optimal chromatographic conditions for the determination of p-toluenesulfonate were using 1.2 mmol/L citric acid-15% acetonitrile(pH 5.0) as mobile phase with a column temperature of 45 ℃ and a flow rate of 1.0 mL/min.Under the optimal conditions,a good separation of p-toluenesulfonate with common inorganic anions(e.g.fluoride,chloride,bromide and nitrate) was obtained.The calibration curve for p-toluenesulfonate was linear in the range of 4.0-100.0 mg/L with a detection limit(S/N=3) of 1.22 mg/L.The relative standard deviations(n=5) for retention time and peak area of p-toluenesulfonate were 0.42% and 1.8%,respectively.The method was successfully applied in the determination of p-toluenesulfonate in ionic liquids with spiked recoveries of 99.6%.This method is simple,accurate,reliable and practical,and could meet the requirements for quantitative analysis of p-toluenesulfonate in ionic liquids.