Objective: To investigate intestinal absorption segments and mechanism of total flavonoids from Sorbus tianschanica leaves in rats. Method: Single-pass intestinal perfusion model was established in rats.The content of total flavonoids in perfusate was determined by HPLC with detection wavelength at 360 nm and mobile phase of acetonitrile and 0.4% phosphoric acid solution in gradient elution.Absorption rate constant (Ka) and apparent absorption coefficient (Papp) were evaluated absorption kinetics of total flavonoids. Result: Six kinds of flavonoids from S. tianschanica leaves could be absorbed in whole intestinal

extent of absorption existed differences in the entire intestinal among different compounds

no difference in absorption was observed in the same compound. Ka and Papp had no significant difference when concentrantions of six kinds of flavonoids was 20-80 mg·L-1.The concentration of flavonoids had no effect on absorption kinetics. Conclusion: Absorption mechanism of six kinds of flavonoids from S. tianschanica leaves is passive diffusion

they are not easily absorbed in the intestine.