Objective,2,To establish a sensitive and rapid high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) method to investigate the pharmacokinetics of antitumor components (Euphorbia factor L2, L3) after intragastric administration, intraperitoneal injection and intravenous injection in rats.,Methods,2,The plasma concentrations of Euphorbia factors L2 and L3 were determined by LC-MS /MS internal standard method. The mobile phase was methanol-water (80: 20). The chromatographic column was BSD Hypersil C,18, (100 mm × 2.1 mm, 3 μm). The column temperature was 30 ℃, the flow rate was 0.2 mL/min, and the injection volume was 5 μL. Mass spectrometry conditions: electrospray ionization (ESI) source, positive ion mode scanning, multi response monitoring mode (MRM) were used to detect the effective components, and pharmacokinetic parameters were calculated by WinNonlin 4.1 pharmacokinetics software.,Results,2,The good linear range of Euphorbia factors L2 and L3 was 5~1 000 ng/mL (,r,2,>, 0.999). The extraction recoveries ranged from 90.5% to 107.2%. The matrix effects ranged from 89.1% to 94.2% and from 88.1% to 93.9%, respectively. The intra-day and inter-day precisions (RSDs, %) were below 12.8%. C,max, and AUC,0-24 h, after intravenous injection of Euphorbia factor L2 and L3 were (20.76±7.55), (13.48±4.59) μg/mL and (8.43±2.34), (5.13±1.38) h·μg,-1,·mL,-1, respectively; C,max, and AUC,0-24 h, after intraperitoneal injection of Euphorbia factor L2 and L3 were (0.95 ±0.26), (0.27±0.06) μg/mL and (3.52±0.90), (0.98±0.29) h·μg,-1,·mL,-1, respectively. After intragastric administration of Euphorbia factors L2 and L3, the concentrations of several samples were lower than the detection limit and could not be detected.,Conclusion,2,The method is sensitive, rapid and selective, and can be used for the simultaneous determination of Euphorbia factors L2 and L3 in rat plasma and its pharmacokinetics. It showed that the bioavailability of Euphorbia factors L2 and L3 were low after intragastric administration, and the exposure dose of Euphorbia factor L2 was higher than that of L3 in rats after intraperitoneal injection.