Abstract: AimTo develop a method of identifying the existing of Panax notoginseng in products of traditional Chinese medicine compound Danshen. MethodsTotal ion chromatograms (TIC) of Panax notoginseng, P.ginseng, and P.quinquefolius were obtained by means of LC/MS. Extracted ion chromatograms (EIC) possess m/z of 770, 800, 932, 946 and 1 108 of above-mentioned three herbs was compared between species. EIC 800 and 946 were selected as differentiation marks to distinguish P.notoginseng from the other two species. The EIC 800 and 946 of P.notoginseng were also compared to the EICs obtained by the same method from Chinese patent medicines of compound Danshen pellet, compound Danshen tablet, and compound Danshen injection. EIC 800 and 946 of P.notoginseng and its products possess similar peaks, relative retention time, and relative integral areas. Main chemical constitutes of P.notoginseng were also identified by using LC/MS/MS. ResultsEIC 800 and 946 were obviously different between P.notoginseng, P.ginseng, and P.quinquefolius. Patent medicines of compound Danshen pellet, compound Danshen tablet, which consist of extractions from P.notoginseng, possess the characteristic EICs. The selected EICs were stable and reproductive. ConclusionEIC 800 and 946, which correspond to ginsenoside Rg1, Re, and their isomers, can be used as identifying mark of P.notoginseng to differentiate it from other herbs, and also can be used to tell apart P.notoginseng from other herb extractions in Chinese patent medicines of compound Danshen.