A simple, sensitive and rapid method for analysis of six lignans in rat plasma after oral administration of Schisandra chinensis extracts, utilizing liquid chromatography tandem mass spectrometry (LC-MS), was established and validated. Plasma samples were prepared by one-step protein precipitation using acetonitrile and the analytes were separated on an SB-C₁₈ column (100 mm × 3.0 mm, 3.5 µm) with the mobile phase of acetonitrile-water at a flow-rate of 0.8 mL/min. Analytes were determined in a single-quadrupole mass spectrometer in the selected ion monitoring (SIM) mode using electrospray source with positive mode. The method was proved to be rapid, sensitive and reproducible, and it was successfully applied to the pharmacokinetic studies of six lignans in rat plasma after oral administration of Schisandra chinensis extracts. In this research, the pharmacokinetics of deoxyschisandrin was also studied following oral administration of the pure deoxyschisandrin. It was found that most of the pharmacokinetic parameters of deoxyschisandrin in the extract were changed significantly compared with those in monomer. The content assay also revealed that the concentrations of the lignan in the extract increased in vivo compared with the pure monomer. Some ingredients in the extract may increase the dissolution of deoxyschisandrin, delay its elimination and enhance its bioavailability in rat.