A one-step method for quantitatively determination of isomaltooligosaccharides(IMO) was developed using high performance anion exchange chromatography coupled with pulsed amperometric detection(HPAEC-PAD).The method was built on a CarboPakTM PA10 column using NaOH and NaAC as eluents.Using this method,besides conventional components of isomaltose,isomaltotriose,panose and some saccharides with higher DP were identified from IMO syrup,other transglycosylation saccharides such as trehalose,kojibiose,nigerose and maltulose were also detected from the syrup.Calibration was carried out by dissolving 15 kinds of standard samples containing glucose,fructose,maltose,maltotriose,isomaltose,isomaltotriose,isomaltotetraose,isomaltopentaose,isomaltohexaose,isomaltoheptaose,panose,trehalose,maltulose,kojibiose,and nigerose into a mixed solution.The standard solution was diluted to a calibration range from 0.032 to 25.975 mg/L.The calibration curves showed good linearity of IMO within this range.The detection limits(LODs) and the quatification limits(LQD) were 0.008～0.022 mg/L and 0.027～0.073 mg/L respectively,and the relative standard deviations were 82.02%～116.37%.This method was good and sensitive in the quantitative analysis of IMO.