Abstract: The aim of this study was to investigate the in vivo pharmacokinetic behavior characteristics and in situ intestinal absorption characteristics of the evodiamine lipidic nanoparticle in rats. Evodiamine lipidic nanoparticle was prepared by the solvent evaporation methods. The particle size and zeta potential of evodiamine lipidic nanoparticle were measured by dynamic light scattering analysis. Male SD rats were divided into two groups randomly. Each group was given single dose of evodiamine and evodiamine lipidic nanoparticle by gavage at evodiamine dose of 250 mg/kg,respectively. The blood samples were collected at scheduled time points. The content of evodiamine in plasma samples was determined by high performance liquid chromatography (HPLC) method. The main pharmacokinetic parameters of evodiamine and evodiamine lipidic nanoparticle were calculated using DAS 2.1.1 software. Moreover,the single-pass intestinal perfusion model was also established in rats to investigate the in situ intestinal absorption characteristics of evodiamine lipidic nanoparticle. The mean particle size and mean zeta potential of evodiamine lipidic nanoparticle were 180.10 nm and -17.90 mV,respectively. The area under the curve of evodiamine and evodiamine lipidic nanoparticle were (862.60±14.03) and (4084.31±17.21) μg/L·h,respectively,and the peak concentration were (163.40±13.27) and (616.90±21.04) μg/L,respectively. Moreover,the absorption of evodiamine lipidic nanoparticle was significantly higher than that of evodiamine in each segment of intestinal tract in rats (P<0.05). The absorption of evodiamine lipidic nanoparticle in colon was better than those of evodiamine lipidic nanoparticle in stomach,duodenum,jejunum and ileum. The absorption rate constant of evodiamine lipidic nanoparticle in stomach,duodenum,jejunum,ileum and colon were (45.10±6.08)×10^-5,(48.20±1.21)×10^-5,(22.10±3.18)×10^-5,(59.10±1.21)×10^-5 and (90.00±3.85)×10^-5 s^-1,respectively,and the effective permeability coefficient in duodenum,jejunum,ileum and colon was (44.10±0.51)×10^-5,(17.21±0.77)×10^-5,(35.36±0.31)×10^-5 and (40.33±0.34)×10^-5 cm/s,respectively.All in all, evodiamine lipidic nanoparticle remarkably improved the in situ intestinal absorption of evodiamine in different segments of the intestinal tract in rats and its oral bioavailability in rats.