Background: Anemarrhenae rhizoma (AR) is widely used for the treatment of febrile diseases, cough, and diabetes in traditional Chinese medicines. AR mainly contains flavonoids and steroidal saponins, such as neomangiferin, mangiferin, timosaponin BII, timosaponin BIII, and timosaponin AIII, which showed various biological activities. Objective: The main objective of the study is to establish an ultra-high-performance liquid chromatography-tandem mass spectrometry (MS/MS) method to determine the concentrations of five bioactive constituents in rats' plasma and various tissues. Materials and Methods: The analytes were separated on a C18reversed-phase column. A triple-quadrupole MS/MS equipped with an electrospray ionization source was used as a detector. The main pharmacokinetic parameters were estimated with Drug and Statistics 2.0 Software Package. Results: Neomangiferin and mangiferin exhibit poor oral absorption and slow clearance from the body. Timosaponin BII and timosaponin BIII could be quickly absorbed into the blood circulation and showed double plasma concentration peaks. Timosaponin AIII exhibited a single peak in the plasma concentration-time plot and pharmacokinetic parameters of timosaponin AIII indicated slower absorption, longer body residence time, and slower elimination than timosaponin BII and timosaponin BIII. The five analytes were widely distributed to most of the tissues. Neomangiferin and mangiferin exhibited the maximum concentration in the lung at 6 h after oral administration, the highest levels of timosaponin BII and timosaponin BIII were also observed in the lung at 1 h after oral administration, and the maximum concentration of timosaponin AIII was observed in the liver. Conclusion: The findings of the present study might be helpful to better understand the pharmacokinetics and distribution of AR bioactive constituents in vivo, which would facilitate the clinical application of AR.