Abstract: The study aims to establish a method analyzing the content of endogenous abscisic acid in salvia miltiorrhiza, and reveal the effect of arbuscular mycorrhizal (AM) on the content of abscisic acid. The abscisic acid analysis was conducted using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). The phytohormone was extracted with 2-propanol: H₂O: concentrated HCl (2:1:0.002, v/v/v), extracted by dichloromethane, and determined using reverse-phase liquid chromatography-tandem mass spectrometry, and the quantitative analysis was carried out with multiple reaction monitoring. In the linear ranges, the correlation coefficient (r) of abscisic acid was 0.9986. The detection limits was 0.0466 ng/mL. The recovery rates of high, medium and low concentration were 80.48%-96.41% in root and leaf. The relative standard deviations (RSD) of inter-day precision and within-day precision were under 10.0%. And RSD values of stability and reproducibility were lower than 5.0%. After inoculated with AM fungi, the content of abscisic acid in root and leaf were significantly lower than the control group. This method had good sensitivity, precision, recovery, and could be used to determine the content of abscisic acid in salvia miltiorrhiza.