Abstract: OBJECTIVE To investigate the in vitro intestinal absorption characteristics of the components in the decoction of Cinnamomi Ramulus and Paeoniae Radix Alba with different proportions in rats and the possible interaction of the components. METHODS The in vitro everted gut sac model combined with HPLC fingerprint were used to determine the change of chemical composition qualitatively and quantitatively before and after intestinal invasion as well as mutual influence of the different ratio of Cinnamomi Ramulus and Paeoniae Radix Alba. RESULTS The results showed that the most components of Cinnamomi Ramulus had good intestinal absorption (P_app>1×10^-5 cm·s^-1), and the ratio of the components was not changed significantly before and after infiltration. The absorption of hydrophilic components represented by paeoniflorin in Paeoniae Radix Alba was better(P_app>1×10^-6 cm·s^-1), but the permeability was deteriorated with the increase of the retention time. The permeation of the two components did not change obviously before and after infiltration. CONCLUSION In addition to some lipophilic components of Paeoniae Radix Alba, most of the components of Cinnamomi Ramulus and Paeoniae Radix Alba are absorbed well, and the combination of the two has little effect on the absorption of each component.