A liquid chromatography coupled with electrospray ionization tandem mass spectrometric（LC-MS/MS） method was developed for the determination of phenazine-1-carboxylic acid in ginseng.The ginseng samples were soaked with water，extracted with acetonitrile and cleaned up by dispersive solid phase extraction，separated by chromatography，then detected by MS/MS under multiple reaction monitoring（MRM） mode via positive electrospray ionization.The ion-pair of 225.1/179.1 was used for quantitative analysis，and the ion-pair of 225.1/125.1 was selected for qualitative analysis.The external standard method was used for the quantification analysis.The limit of quantitation（LOQ） of phenazine-1-carboxylic acid was 0.01 mg/kg.The standard calibration curve was linear in the range of 0.5-10 μg/L，with correlation coefficient more than 0.99.The recoveries of phenazine-1-carboxylic acid in ginseng were in the range of 82%-100% at three spiked levels of 0.01，0.02 and 0.10 mg/kg，with relative standard deviations（RSDs） not more than 6.8%.The result showed that the method was simple，rapid and highly sensitive,and could be applied in the determination of phenazine-1-carboxylic acid in ginseng.