Abstract: AimTo survey the morphology and size distribution of silymarin microemulsion, to investigate the absorption of silymarin microemulsion in rat intestine compared with the absorption of silymarin micelle in rat Jejunum. MethodsThe intestine in rats was canulated for in situ recirculation. ResultsThe absorption rate constants (k_a) of silymarin microemulsion at the entire intestine, ileum , jejunum, duodenum and colon were 6.22×10^-2, 2.27×10^-2, 1.9×10^-2, 1.05×10^-2 and 0.43×10^-2 h^-1 , respectively. The absorption rate constants of two kinds of silymarin micelle at jejunum were 0.36×10^-2, 0.65×10^-2 h^-1 . ConclusionSilymarin microemulsion was well absorbed at the middle and lower segments of intestine in rats. The absorption was a first-order process with the passive diffusion mechanism.