Objective To study the in situ intestinal absorption characteristics of cyclovirobuxine D (CB) hydroxypropyl-β-cyclodextrin inclusion complex (CBHD) in rats, and to explore the effect of cytochrome P450 inhibitor ketoconazole (KET) on CB and CBHD in situ intestinal absorption. Methods Twenty-four male rats were randomized into CB, CBHD, KET+CB and KET+CBHD groups, with 6 rats in each group. In situ intestinal absorption was adopted in a rat model. One-way intestinal perfusion model was employed to investigate the absorption of CB and CBHD in the intestinal segments of rats and the effects of KET on CB and CBHD absorption. The concentration of CB was determined by highperformance liquid chromatography with fluorescence detector (HPLC/FLD; Lichrospher C₁₈ column[250 mm×4.6 mm, 5 μm]). The mobile phase was methanol-water with volume ratio being 85︰15. The excitation wavelength was set at 231 nm, and emission wavelength was set at 385 nm. The column temperature was 25℃, and flow rate was 1.0 mL/min. The injection volume was 20 μL. Results The specificity of HPLC/FLD method was good and the standard curve equation was A=106.7 C+41.861 (R²=0.999 08) based on the linear regression of CB concentration (C) with CB peak area (A), indicating that the CB mass concentration was linear in the range of 0.5 to 20.0 μg/mL. The intra-day precision of the 1.0, 5.0 and 10.0 μg/mL samples was 2.25%, 2.44% and 3.04%, and the inter-day precision was 4.22%, 2.00% and 2.50%, respectively. The precision was good and the method was in accordance with the requirements of methodology. The recovery rates of the 1.0, 5.0 and 10.0 μg/mL samples were 99.08%, 98.24% and 97.25%, respectively, which were also in accordance with the requirements of methodology. The intestinal absorption rate constant (Ka) values of CBHD with KET were 4.18, 5.05, 1.91 and 2.85 times those of CB, and the effective permeability (P_eff) values were 4.92, 5.98, 2.19 and 3.24 times those of CB in the duodenum, jejunum, ileum and colon, respectively (all P<0.05). Conclusion KET can improve the intestinal absorption of CB and CBHD in rats.