Objective: The objective of the study was to develop a rapid and sensitive ultra?performance liquid chromatography?tandem mass spectrometric method for the determination of tetrandrine, fangchinoline, and cyclanoline in rat plasma and to investigate their pharmacokinetics after oral administration of Stephaniae Tetrandrae Radix extracts. Methods: Sample pretreatment involved methanol pretreatment and liquid–liquid extraction of ethyl acetate from plasma with methanol. Tramadol was used as the internal standard. The analysis was performed using an high strength silica T3 column (100 mm × 2.1 mm, 1.8 μm) and a gradient elution method consisting of mobile phase solution A (0.1％ formic acid in water) and B (acetonitrile) at a flow rate of 0.4 mL/min. The detection was performed using a triple quadrupole tandem mass spectrometer in the multiple reaction monitoring mode and using an electrospray ionization source in the positive ionization mode. Results: High efficiency was achieved with an analysis time of 4 min/sample. The calibration curve linear in the concentration range of 1250 ng/ml (R2 ≥ 0.9900) and the lower limit of quantification is 1 ng/ml. The intraday and interday precision (relative standard deviation) values were lower than 9.4. Accuracy (relative error) was within 10.3％ at all three quality control levels. Conclusions: This method was successfully applied in pharmacokinetics of tetrandrine, fangchinoline, and cyclanoline in rats after oral administration of Stephaniae Tetrandrae Radix extracts. The maximum plasma concentration (Cmax) of tetrandrine, fangchinoline, and cyclanoline was 124.71 ± 16.08, 84.56 ± 3.28, and 57.61 ± 6.26 ng/mL, respectively. The time to reach Cmax was 10.39 ± 3.04 for tetrandrine, 10.17 ± 3.04 for fangchinoline, and 6.40 ± 3.16 for cyclanoline. The pharmacokinetic results might help further guide the clinical application of Stephaniae Tetrandrae Radix.